Human Cyclin-dependent Kinase Inhibitor 1, CDKN1A ELI

May be involved in p53/TP53 mediated inhibition of cellular proliferation in response to DNA damage.

Binds to and inhibits cyclin-dependent kinase activity, preventing phosphorylation of critical cyclin-dependent kinase substrates and blocking cell cycle progression.

Functions in the nuclear localization and assembly of cyclin D-CDK4 complex and promotes its kinase activity towards RB1.

At higher stoichiometric ratios, inhibits the kinase activity of the cyclin D-CDK4 complex.

Inhibits DNA synthesis by DNA polymerase delta by competing with POLD3 for PCNA binding (PubMed: 11595739).

Plays an important role in controlling cell cycle progression and DNA damage-induced G2 arrest (PubMed: 9106657).