This family represents the C-terminal region of BTB/POZ domain-containing protein KCTD11 (known as REN: EGF-, NGF- and retinoic acid-responsive gene) and one homologue, a member of KCTD containing, Cullin3 adaptor, suppressor of Hedgehog (KCASH) family, KCASH2-KCTD21 protein. They share high similarity and a BTB domain responsible for oligomerization and formation of a Cullin3 ubiquitin ligase complex, specific expression in brain and cerebellum where they have a role in neuronal differentiation, and suppressor activity on acetylation-dependent Hedgehog/Gli signalling through ubiquitination and degradation of histone deacetylase 1. These proteins have been described as tumor suppressors that inhibit medulloblastoma growth by antagonizing Hedgehog signalling [1,2].

1: Identification and characterization of KCASH2 and KCASH3, 2 novel Cullin3 adaptors suppressing histone deacetylase and Hedgehog activity in medulloblastoma. De Smaele E, Di Marcotullio L, Moretti M, Pelloni M, Occhione MA, Infante P, Cucchi D, Greco A, Pietrosanti L, Todorovic J, Coni S, Canettieri G, Ferretti E, Bei R, Maroder M, Screpanti I, Gulino A; Neoplasia. 2011;13:374-385. PMID:21472142

2: Hedgehog antagonist REN(KCTD11) regulates proliferation and apoptosis of developing granule cell progenitors. Argenti B, Gallo R, Di Marcotullio L, Ferretti E, Napolitano M, Canterini S, De Smaele E, Greco A, Fiorenza MT, Maroder M, Screpanti I, Alesse E, Gulino A; J Neurosci. 2005;25:8338-8346. PMID:16148242