p57 Kip2 Recombinant Rabbit mAb (S-6119)

p57 Kip2 (also known as CDKN1C) is a member of the Cip/Kip family encoded by the paternally imprinted gene CDKN1C, and is the only member of this family that is essential for embryonic development. Human CDKN1C is located on chromosome 11p15.5 and is expressed only from the maternal allele, with its transcription regulated by the ICR2 imprinting control region and the KCNQ1OT1 non-coding RNA. p57 Kip2 is a potent, tightly binding inhibitor of G1-phase cyclin/CDK complexes (such as cyclin E-CDK2 and cyclin D2-CDK4), and its overexpression can cause complete cell cycle arrest in G1 phase. Its structure consists of an N-terminal CDK inhibitory domain, a proline-rich domain, an acidic repeat region, and a C-terminal nuclear localization domain, with nuclear localization depending on a classical bipartite nuclear localization signal formed by two positively charged clusters. Functionally, p57 Kip2 is highly expressed in terminally differentiated tissues such as skeletal muscle, heart, brain, and lung, participating in cell cycle exit and differentiation regulation. Loss of its function is associated with Beckwith-Wiedemann syndrome (overgrowth), while missense mutations in the PCNA-binding domain cause IMAGe syndrome (growth restriction). In addition, p57 Kip2 expression is downregulated in various cancers, but mutations in the gene itself are rare, suggesting that its tumor suppressor function is mainly inactivated through epigenetic silencing.