p27kip1

A cyclin-dependent kinase inhibitor which binds to cyclinE/cdk2, blocking the G1/S transition step required for cell cycle progression. It is upregulated by cell stress, resulting in inhibition of cell cycling and apoptosis, and may have a role in tumour supression, cell migration and mitosis; low p27 expression has been reported in breast, colourectal, gastric, lung and brain cancer. Decreased p27 expression is associated with a poorer prognosis. p27 is downregulated through degradation by ubiquitin-dependent proteolysis