The antibody detects endogenous levels of total CDKN2B protein. The four known 15-to 19 kDa INK4 proteins (p15INK4b, p16INK4a, p18INK4c andp19INK4d) bind and inhibit CDK4 and CDK6 but not other CDKs, including cyclin E-Cdk2, cyclin A-Cdk2 and cyclin B-Cd