CPL4 (C-TERMINAL DOMAIN PHOSPHATASE-LIKE 4); phosphoprotein phosphatase; Encodes a polypeptide that contains FCPH and BRCT domains. RNAi suppression mutant lines were generated, which displayed a range of phenotypic abnormalities, including- incomplete to no cotyledon expansion, slow growth, epinastic leaves or small inflorescences. ; Processively dephosphorylates 'Ser-2' and/or 'Ser-5' of the heptad repeats YSPTSPS in the C-terminal domain of the largest RNA polymerase II subunit (RPB1). This promotes the activity of RNA polymerase II (By similarity). Required for normal plant growth (440 aa)