p57 (C-20) Antibody: sc-1040

p57 Background Information
Cell cycle progression is regulated by a series of cyclin-dependent kinases that consist of catalytic subunits designated Cdks and activating subunits designated cyclins. Orderly progression through the cell cycle requires the activation and inactivation of different cyclin-Cdks at appropriate times. A series of proteins has been described that function as mitotic inhibitors. These include p21, the levels of which are elevated upon DNA damage in G1 in a p53-dependent manner; p16; and p16-related inhibitors, designated p15, p18 and p19. A p21-related protein, p27, has been described as a negative regulator of G1 progression and has been speculated to function as a possible mediator of TGF b-induced G1 arrest. A member of the p21/p27 family of mitotic inhibitory proteins, p57 (also designated Kip2), is a potent, tight-binding cyclin-dependent inhibitor of several G1 cyclin/Cdk complexes. Overexpression of p57 arrests cells in G1. Unlike p21, p57 is not regulated by p53.