| GOID Link to GO |
Functional Category | Description | Protein Count link to protein list |
|---|---|---|---|
| GO:0004993 | serotonin receptor activity | Combining with the biogenic amine serotonin and transmitting the signal across the membrane by activating an associated G-protein. Serotonin (5-hydroxytryptamine) is a neurotransmitter and hormone found in vertebrates and invertebrates. | 26 |
| GO:0008188 | neuropeptide receptor activity | Combining with a neuropeptide to initiate a change in cell activity. | 22 |
| GO:0001653 | peptide receptor activity | Combining with an extracellular or intracellular peptide to initiate a change in cell activity. | 19 |
| GO:0009881 | photoreceptor activity | The function of absorbing and responding to incidental electromagnetic radiation, particularly visible light. The response may involve a change in conformation. | 18 |
| GO:0004989 | octopamine receptor activity | Combining with the biogenic amine octopamine to initiate a change in cell activity. Octopamine is found in both vertebrates and invertebrates and can have properties both of a hormone and a neurotransmitter and acts as an adrenergic agonist. | 17 |
| GO:0015464 | acetylcholine receptor activity | Combining with acetylcholine and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 15 |
| GO:0004930 | G-protein coupled receptor activity | Combining with an extracellular signal and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. | 14 |
| GO:0004714 | transmembrane receptor protein tyrosine kinase activity | Combining with a signal and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity by catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate. | 13 |
| GO:0004938 | alpha2-adrenergic receptor activity | Combining with epinephrine or norepinephrine to initiate a change in cell activity via activation of a G protein, with pharmacological characteristics of alpha2-adrenergic receptors; the activity involves transmitting the signal to the Gi alpha subunit of a heterotrimeric G protein. | 12 |
| GO:0004952 | dopamine neurotransmitter receptor activity | Combining with the neurotransmitter dopamine to initiate a change in cell activity. | 12 |
| GO:0015277 | kainate selective glutamate receptor activity | An ionotropic glutamate receptor activity that exhibits fast gating by glutamate, acts by opening a cation channel permeable to sodium and potassium, and for which kainate is an agonist. | 12 |
| GO:0042813 | Wnt-activated receptor activity | Combining with a Wnt protein and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 11 |
| GO:0000155 | phosphorelay sensor kinase activity | Catalysis of the phosphorylation of a histidine residue in response to detection of an extracellular signal such as a chemical ligand or change in environment, to initiate a change in cell state or activity. The two-component sensor is a histidine kinase that autophosphorylates a histidine residue in its active site. The phosphate is then transferred to an aspartate residue in a downstream response regulator, to trigger a response. | 11 |
| GO:0004886 | 9-cis retinoic acid receptor activity | Combining with 9-cis retinoic acid and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription by RNA polymerase II. | 11 |
| GO:0004985 | opioid receptor activity | Combining with an opioid (any narcotic derived from or resembling opium), and transmitting the signal across the membrane by activating an associated G-protein. | 11 |
| GO:0016941 | natriuretic peptide receptor activity | Combining with a natriuretic peptide and transmitting the signal to initiate a change in cell activity. | 10 |
| GO:0003707 | steroid hormone receptor activity | Combining with a steroid hormone and transmitting the signal within the cell to initiate a change in cell activity or function. | 9 |
| GO:0004890 | GABA-A receptor activity | Combining with the amino acid gamma-aminobutyric acid (GABA, 4-aminobutyrate) to initiate a change in cell activity. GABA-A receptors function as chloride channels. | 9 |
| GO:0004971 | alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate selective glutamate receptor activity | An ionotropic glutamate receptor activity that exhibits fast gating by glutamate and acts by opening a cation channel permeable to sodium, potassium, and, in the absence of a GluR2 subunit, calcium. | 9 |
| GO:0004702 | receptor signaling protein serine/threonine kinase activity | Conveys a signal from an upstream receptor or intracellular signal transducer by catalysis of the reaction: ATP protein serine = ADP + protein serine phosphate, and ATP + protein threonine = ADP + protein threonine phosphate. | 9 |
| GO:0038023 | signaling receptor activity | Receiving a signal and transmitting the signal in the cell to initiate a change in cell activity. A signal is a physical entity or change in state that is used to transfer information in order to trigger a response. | 8 |
| GO:0001601 | peptide YY receptor activity | Combining with gut peptide YY to initiate a change in cell activity. | 8 |
| GO:0005057 | receptor signaling protein activity | Conveys a signal from an upstream receptor or intracellular signal transducer, converting the signal into a form where it can ultimately trigger a change in the state or activity of a cell. | 8 |
| GO:0004705 | JUN kinase activity | Catalysis of the reaction: JUN + ATP = JUN phosphate + ADP. This reaction is the phosphorylation and activation of members of the JUN family, a gene family that encodes nuclear transcription factors. | 8 |
| GO:0001640 | adenylate cyclase inhibiting G-protein coupled glutamate receptor activity | Combining with glutamate and transmitting the signal across the membrane by activating the alpha-subunit of an associated heterotrimeric G-protein complex to inhibit downstream adenylate cyclase activity. | 7 |
| GO:0004707 | MAP kinase activity | Catalysis of the reaction: protein + ATP = protein phosphate + ADP. This reaction is the phosphorylation of proteins. Mitogen-activated protein kinase; a family of protein kinases that perform a crucial step in relaying signals from the plasma membrane to the nucleus. They are activated by a wide range of proliferation- or differentiation-inducing signals; activation is strong with agonists such as polypeptide growth factors and tumor-promoting phorbol esters, but weak (in most cell backgrounds) by stress stimuli. | 7 |
| GO:0004995 | tachykinin receptor activity | Combining with a tachykinin neuropeptide and transmitting the signal across the membrane by activating an associated G-protein. | 7 |
| GO:0008528 | G-protein coupled peptide receptor activity | Combining with a peptide and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. | 7 |
| GO:0004888 | transmembrane signaling receptor activity | Combining with an extracellular or intracellular signal and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 7 |
| GO:0008046 | axon guidance receptor activity | Combining with an extracellular messenger and transmitting the signal from one side of the membrane to the other to results in a change in cellular activity involved in axon guidance. | 7 |
| GO:0008020 | G-protein coupled photoreceptor activity | Combining with incidental electromagnetic radiation, particularly visible light, and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. | 6 |
| GO:0004709 | MAP kinase kinase kinase activity | Catalysis of the phosphorylation and activation of a MAP kinase kinase; each MAP kinase kinase can be phosphorylated by any of several MAP kinase kinase kinases. | 6 |
| GO:0005004 | GPI-linked ephrin receptor activity | Combining with a GPI-anchored ephrin to initiate a change in cell activity. | 6 |
| GO:0005001 | transmembrane receptor protein tyrosine phosphatase activity | Combining with a signal and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity by catalysis of the reaction: protein tyrosine phosphate + H2O = protein tyrosine + phosphate. | 6 |
| GO:0004879 | ligand-activated sequence-specific DNA binding RNA polymerase II transcription factor activity | Combining with a signal and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription by RNA polymerase II. | 6 |
| GO:0004935 | adrenergic receptor activity | Combining with epinephrine or norepinephrine and transmitting the signal across the membrane by activating the alpha-subunit of an associated heterotrimeric G-protein complex. | 5 |
| GO:0004996 | thyroid-stimulating hormone receptor activity | Combining with thyroid-stimulating hormone to initiate a change in cell activity. | 5 |
| GO:0030594 | neurotransmitter receptor activity | Combining with a neurotransmitter and transmitting the signal to initiate a change in cell activity. | 5 |
| GO:0005005 | transmembrane-ephrin receptor activity | Combining with a transmembrane ephrin to initiate a change in cell activity. | 5 |
| GO:0004716 | receptor signaling protein tyrosine kinase activity | Conveys a signal from an upstream receptor or intracellular signal transducer by catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate. | 5 |
| GO:0001591 | dopamine neurotransmitter receptor activity, coupled via Gi/Go | Combining with the neurotransmitter dopamine and activating adenylate cyclase via coupling to Gi/Go to initiate a change in cell activity. | 4 |
| GO:0009882 | blue light photoreceptor activity | The function of absorbing and responding to electromagnetic radiation with a wavelength of approximately 400-470nm. The response may involve a change in conformation. | 4 |
| GO:0016361 | activin receptor activity, type I | Combining with activin-bound type II activin receptor to initiate a change in cell activity; upon binding, acts as a downstream transducer of activin signals. | 4 |
| GO:0030618 | transforming growth factor beta receptor, pathway-specific cytoplasmic mediator activity | A TGF-beta cytoplasmic mediator that is phosphorylated by a TGFbeta receptor and complexes with a common-partner mediator. The- heterocomplex translocates to the nucleus to regulate transcription. | 4 |
| GO:0030108 | HLA-A specific activating MHC class I receptor activity | Combining with a MHC class I molecule of the HLA-A subclass to mediate signaling that activates a lymphocyte. | 4 |
| GO:0005025 | transforming growth factor beta receptor activity, type I | Combining with a complex of transforming growth factor beta and a type II TGF-beta receptor to initiate a change in cell activity; upon binding, acts as a downstream transducer of TGF-beta signals. | 4 |
| GO:0034188 | apolipoprotein A-I receptor activity | Combining with apolipoprotein A-I and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 4 |
| GO:0016500 | protein-hormone receptor activity | Combining with a protein hormone to initiate a change in cell activity. | 4 |
| GO:0005010 | insulin-like growth factor-activated receptor activity | Combining with insulin-like growth factor and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 3 |
| GO:0033038 | bitter taste receptor activity | Combining with soluble bitter compounds to initiate a change in cell activity. These receptors are responsible for the sense of bitter taste. | 3 |
| GO:0030616 | transforming growth factor beta receptor, common-partner cytoplasmic mediator activity | A TGF-beta cytoplasmic mediator that forms a complex with a phosphorylated pathway-specific mediator. The heterocomplex translocates to the nucleus to regulate transcription. | 3 |
| GO:0005009 | insulin-activated receptor activity | Combining with insulin and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 3 |
| GO:0010465 | nerve growth factor receptor activity | Combining with nerve growth factor (NGF), to block apoptosis in neurons and promote nerve growth, or to initiate a change in cell activity. | 3 |
| GO:0008502 | melatonin receptor activity | Combining with melatonin, N-acetyl-5-methoxytryptamine, to initiate a change in cell activity. Melatonin is a neuroendocrine substance that stimulates the aggregation of melanosomes in melanophores, thus lightening the skin. | 3 |
| GO:0009400 | receptor signaling protein serine/threonine phosphatase activity | Conveys a signal from an upstream receptor or intracellular signal transducer by catalysis of the reaction: protein serine phosphate + H2O = protein serine + phosphate, and protein threonine phosphate + H2O = protein threonine + phosphate. | 3 |
| GO:0008227 | G-protein coupled amine receptor activity | Combining with an extracellular amine and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. | 3 |
| GO:0005007 | fibroblast growth factor-activated receptor activity | Combining with a fibroblast growth factor and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 2 |
| GO:0001594 | trace-amine receptor activity | Combining with a trace amine to initiate a change in cell activity. Trace amines are biogenic amines that are synthesized from aromatic amino acids and are substrates for monoamine oxidase, and are therefore detectable only at trace levels in mammals. | 2 |
| GO:0008503 | benzodiazepine receptor activity | Combining with benzodiazepines, a class of drugs with hypnotic, anxiolytic, anticonvulsive, amnestic and myorelaxant properties, to initiate a change in cell activity. | 2 |
| GO:0004874 | aryl hydrocarbon receptor activity | Combining with an aryl hydrocarbon and transmitting the signal to initiate a change in cell activity. The aryl hydrocarbon receptor is a ligand-activated transcription factor which translocates to the nucleus to activate transcription upon ligand-binding. | 2 |
| GO:0005000 | vasopressin receptor activity | Combining with vasopressin to initiate a change in cell activity. | 2 |
| GO:0008261 | allatostatin receptor activity | Combining with allatostatin to initiate a change in cell activity. | 2 |
| GO:0016917 | GABA receptor activity | Combining with gamma-aminobutyric acid (GABA), and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. (GABA, 4-aminobutyrate) is an amino acid which acts as a neurotransmitter in some organisms. | 2 |
| GO:0008349 | MAP kinase kinase kinase kinase activity | Catalysis of the phosphorylation of serine and threonine residues in a mitogen-activated protein kinase kinase kinase (MAPKKK), resulting in activation of MAPKKK. MAPKKK signaling pathways relay, amplify and integrate signals from the plasma membrane to the nucleus in response to a diverse range of extracellular stimuli. | 2 |
| GO:0001588 | dopamine neurotransmitter receptor activity, coupled via Gs | Combining with the neurotransmitter dopamine and activating adenylate cyclase via coupling to Gs to initiate a change in cell activity. | 2 |
| GO:0005220 | inositol 1,4,5-trisphosphate-sensitive calcium-release channel activity | Catalysis of the transmembrane transfer of a calcium ion by a channel that opens when inositol 1,4,5-trisphosphate (IP3) has been bound by the channel complex or one of its constituent parts. | 2 |
| GO:0008066 | glutamate receptor activity | Combining with glutamate and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 2 |
| GO:0001595 | angiotensin receptor activity | Combining with angiotensin to initiate a change in cell activity. | 2 |
| GO:0038062 | protein tyrosine kinase collagen receptor activity | Combining with collagen and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity by catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate. | 2 |
| GO:0004970 | ionotropic glutamate receptor activity | Catalysis of the transmembrane transfer of an ion by a channel that opens when glutamate has been bound by the channel complex or one of its constituent parts. | 2 |
| GO:0042656 | JUN kinase kinase kinase kinase activity | Catalysis of the phosphorylation and activation of JUN kinase kinase kinases (JNKKKs). | 2 |
| GO:0008036 | diuretic hormone receptor activity | Combining with a diuretic hormone and transmitting the signal to initiate a change in cell activity. | 2 |
| GO:0038052 | estrogen-activated sequence-specific DNA binding RNA polymerase II transcription factor activity | Combining with estrogen and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription by RNA polymerase II. | 2 |
| GO:0004706 | JUN kinase kinase kinase activity | Catalysis of the reaction: JNKK + ATP = JNKK phosphate + ADP. This reaction is the phosphorylation and activation of JUN kinase kinases (JNKKs). | 2 |
| GO:0004887 | thyroid hormone receptor activity | Combining with thyroid hormone and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription by RNA polymerase II. | 2 |
| GO:0004704 | NF-kappaB-inducing kinase activity | Catalysis of the phosphorylation of the alpha or beta subunit of the inhibitor of kappaB kinase complex (IKK). | 2 |
| GO:0004728 | receptor signaling protein tyrosine phosphatase activity | Conveys a signal from an upstream receptor or intracellular signal transducer by catalysis of the reaction: protein tyrosine phosphate + H2O = protein tyrosine + phosphate. | 2 |
| GO:0071936 | coreceptor activity involved in Wnt receptor signaling pathway | Combining with an extracellular messenger, and in cooperation with a primary Wnt receptor, initiating a change in cell activity through the Wnt receptor signaling pathway. | 2 |
| GO:0015056 | corticotrophin-releasing factor receptor activity | Combining with the corticotrophin-releasing factor family of ligands, including the urocortins, to initiate a change in cell activity. | 1 |
| GO:0004972 | N-methyl-D-aspartate selective glutamate receptor activity | An ionotropic glutamate receptor activity that exhibits slow gating by glutamate, acts by opening a nonselective cation channel, and can be activated by L-aspartate. | 1 |
| GO:0016496 | substance P receptor activity | Combining with substance P, the peptide Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met, to initiate a change in cell activity. | 1 |
| GO:0038025 | reelin receptor activity | Combining with the secreted glycoprotein reelin, and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 1 |
| GO:0036327 | VEGF-B-activated receptor activity | Combining with vascular endothelial growth factor B (VEGF-B) and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 1 |
| GO:0036332 | placental growth factor-activated receptor activity | Combining with placental growth factor (PlGF) and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 1 |
| GO:0005003 | ephrin receptor activity | Combining with an ephrin to initiate a change in cell activity. | 1 |
| GO:0001565 | phorbol ester receptor activity | Combining with a phorbol ester and transmitting the signal to initiate a change in cell activity. | 1 |
| GO:0042801 | polo kinase kinase activity | Catalysis of the addition of a phosphate group onto a serine or threonine residue in any member of the polo kinase class of proteins. | 1 |
| GO:0008527 | taste receptor activity | Combining with soluble compounds to initiate a change in cell activity. These receptors are responsible for the sense of taste. | 1 |
| GO:0005026 | transforming growth factor beta receptor activity, type II | Combining with transforming growth factor beta to initiate a change in cell activity; upon ligand binding, binds to and catalyzes the phosphorylation of a type I TGF-beta receptor. | 1 |
| GO:0004882 | androgen receptor activity | Combining with an androgen and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with an androgen response element in DNA in order to modulate transcription by RNA polymerase II. | 1 |
| GO:0042071 | leucokinin receptor activity | Combining with a leucokinin, any of several octapeptide hormones found in insects, and transmitting the signal to initiate a change in cell activity. | 1 |
| GO:0004958 | prostaglandin F receptor activity | Combining with prostaglandin F (PGF (2-alpha)) to initiate a change in cell activity. | 1 |
| GO:0036326 | VEGF-A-activated receptor activity | Combining with vascular endothelial growth factor A (VEGF-A) and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 1 |
| GO:0043404 | corticotropin-releasing hormone receptor activity | Combining with corticotropin-releasing hormone and transmitting the signal to initiate a change in cell activity. | 1 |
| GO:0004941 | beta2-adrenergic receptor activity | Combining with epinephrine or norepinephrine to initiate a change in cell activity via activation of a G protein, with pharmacological characteristics of beta2-adrenergic receptors. | 1 |
| GO:0004939 | beta-adrenergic receptor activity | Combining with epinephrine or norepinephrine to initiate a change in cell activity via activation of a G protein, with pharmacological characteristics of beta-adrenergic receptors; the activity involves transmitting the signal to the Gs alpha subunit of a heterotrimeric G protein. | 1 |
| GO:0016909 | SAP kinase activity | Catalysis of the phosphorylation of proteins. A family of protein kinases that perform a crucial step in relaying signals from the plasma membrane to the nucleus. Strongly activated by stress signals such as heat or osmotic shock, DNA-damaging agents, inhibitors of protein synthesis and pro-inflammatory cytokines. | 1 |
| GO:0016362 | activin receptor activity, type II | Combining with activin to initiate a change in cell activity; upon ligand binding, binds to and catalyses the phosphorylation of a type I activin receptor. | 1 |
| GO:0015026 | coreceptor activity | Combining with an extracellular or intracellular messenger, and in cooperation with a nearby primary receptor, initiating a change in cell activity. | 1 |
| GO:0017154 | semaphorin receptor activity | Combining with a semaphorin, and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 1 |
| GO:0005021 | vascular endothelial growth factor-activated receptor activity | Combining with a vascular endothelial growth factor (VEGF) and transmitting the signal across the plasma membrane to initiate a change in cell activity. | 1 |
| GO:0008281 | sulfonylurea receptor activity | Combining with sulfonylurea, and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. | 1 |
| GO:0016494 | C-X-C chemokine receptor activity | Combining with a C-X-C chemokine and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. A C-X-C chemokine has a single amino acid between the first two cysteines of the characteristic four cysteine motif. | 1 |
| GO:0008226 | tyramine receptor activity | Combining with the biogenic amine tyramine to initiate a change in cell activity. Tyramine is a sympathomimetic amine derived from tyrosine with an action resembling that of epinephrine. | 1 |
| GO:0030284 | estrogen receptor activity | Combining with estrogen and transmitting the signal within the cell to trigger a change in cell activity or function. | 1 |
| GO:0005072 | transforming growth factor beta receptor, cytoplasmic mediator activity | Activity of any of the molecules that transmit the signal from a TGF-beta receptor through the cytoplasm to the nucleus. | 1 |
| GO:0016493 | C-C chemokine receptor activity | Combining with a C-C chemokine and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity. C-C chemokines do not have an amino acid between the first two cysteines of the characteristic four-cysteine motif. | 1 |
| GO:0016497 | substance K receptor activity | Combining with substance K, the peptide His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met, to initiate a change in cell activity. | 1 |
| GO:0003708 | retinoic acid receptor activity | Combining with retinoic acid and transmitting the signal to the transcriptional machinery by interacting selectively and non-covalently with a specific DNA sequence in order to modulate transcription by RNA polymerase II. Retinoic acid is one of the forms of vitamin A. | 1 |
| GO:0004957 | prostaglandin E receptor activity | Combining with prostaglandin E (PGE(2)) to initiate a change in cell activity. | 1 |
| GO:0005024 | transforming growth factor beta-activated receptor activity | Combining with a transforming growth factor beta (TGFbeta) and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity by catalysis of the reaction: ATP protein serine = ADP + protein serine phosphate, and ATP + protein threonine = ADP + protein threonine phosphate. | 1 |
| GO:0016907 | G-protein coupled acetylcholine receptor activity | Combining with acetylcholine and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex. | 1 |
| GO:0060182 | apelin receptor activity | Combining with the peptide apelin to initiate a change in cell activity. | 1 |
| GO:0001602 | pancreatic polypeptide receptor activity | Combining with pancreatic polypeptide PP to initiate a change in cell activity. | 1 |
| GO:0009927 | histidine phosphotransfer kinase activity | Serves as a phospho-His intermediate enabling the transfer of phospho group between a hybrid kinase and a response regulator. | 1 |
| GO:0005020 | stem cell factor receptor activity | Combining with stem cell factor (SCF) and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity by catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate. Stem cell factor is a cytokine that stimulates mast cell growth and differentiation. | 1 |