May negatively regulate cell cycle progression. May act at least in part via inhibition of the cyclin-D1/CDK4 complex, thereby preventing phosphorylation of RB1 and blocking E2F-dependent transcription (By similarity). Interacts with CCND1 and GRAP2. May also interact with COPS5, RPLP0, SIRT6, SYF2 and TCF3. Expression is induced by partial hepatectomy. Phosphorylated. Belongs to the CCNDBP1 family.