May play a critical role in inducing the cell cycle arrest via inhibiting CCND1 expression in all-trans-retinoic acid (ATRA) signal pathway. Up-regulated by all-trans-retinoic acid (ATRA) in several tumor cell lines. Weakly expressed in hematopoietic cell lines. 3 isoforms of the human protein are produced by alternative promoter. Note: This description may include information from UniProtKB.