. "Prior to mitogen activation, the inhibitory proteins, INK4 (p15, p16, p18, and p19) associate with the catalytic domain of free CDK4/6, preventing its association with cyclin, and thus its activation."^^ . "Edited: Matthews, L, 2005-10-07 06:13:50"^^ . . . . . . . . . "Association of INK4A with Cdk4/6"^^ . . . .