Cyclin-dependent kinase binding protein. Enhances cyclin-dependent kinase tyrosine phosphorylation by nonreceptor tyrosine kinases, such as that of CDK5 by activated ABL1, which leads to increased CDK5 activity and is critical for neuronal development, and that of CDK2 by WEE1, which leads to decreased CDK2 activity and growth inhibition. Positively affects neuronal outgrowth. Plays a role as a regulator for p53/p73-induced cell death (By similarity). Found in a complex with p53/TP53. Found in a number of complexes with CDK2, CDK3, CDK5, ABL1, TDRD7, CDK17, CCNA1, CCNE1 and TP73. Interacts with CDK2, CDK3, CDK5, ABL1 and TDRD7 (By similarity). Located in the cell body and proximal region of the developing axonal shaft of immature neurons. Located in axonal growth cone, but not in the distal part of the axon shaft or in dendritic growth cone of mature neurons (By similarity). Expressed in breast, pancreas, colon, head and neck (at protein level). Strongly decreased in more than half of cases of atypical endometrial hyperplasia and in more than 90% of endometrial cancers. Expression in the endometrial epithelium fluctuates during the menstrual cycle, being greater during the secretory phase when compared with the proliferative phase. Up-regulated by progesterone and down-regulated by estrogen in benign endometrium. Phosphorylated on Ser-313 by CCNE1/CDK3. Phosphorylated on serine/threonine residues by CDK5 and on tyrosine residues by ABL1. Also phosphorylated in vitro by CCNA1/CDK2, CCNE1/CDK2, CCNA1/CDK3 and CCNE1/CDK3 (By similarity). Belongs to the cyclin family.