This gene encodes a potent cyclin-dependent kinase
inhibitor. The encoded protein binds to and inhibits the activity
of cyclin-CDK2 or -CDK4 complexes, and thus functions as a
regulator of cell cycle progression at G1. The expression of this
gene is tightly controlled by the tumor suppressor protein p53,
through which this protein mediates the p53-dependent cell cycle G1
phase arrest in response to a variety of stress stimuli. This
protein can interact with proliferating cell nuclear antigen
(PCNA), a DNA polymerase accessory factor, and plays a regulatory
role in S phase DNA replication and DNA damage repair. This protein
was reported to be specifically cleaved by CASP3-like caspases,
which thus leads to a dramatic activation of CDK2, and may be
instrumental in the execution of apoptosis following caspase
activation. Multiple alternatively spliced variants have been found
for this gene.
