BTB/POZ domain-containing protein KCTD21 (KCTD21)

Probable substrate-specific adapter of a BCR (BTB-CUL3- RBX1) E3 ubiquitin-protein ligase complex mediating the ubiquitination and subsequent proteasomal degradation of target proteins. Promotes the ubiquitination of HDAC1.

Can function as antagonist of the Hedgehog pathway by affecting the nuclear transfer of transcription factor GLI1; the function likely occurs via HDAC1 down-regulation, maintaining GLI1 acetylated and inactive. Inhibits cell growth and tumorigenicity of medulloblastoma (MDB) (PubMed:21472142).