In a preferred embodiment, the CCR anatagonist is a peptide or non-peptide analog of the amino acid sequence VAEIG(V/E)GAYG(T/K)V(F/Y)KARD, though more preferably a peptidomimetic of the amino acid sequence V(F/Y)KARD, and even more preferably of the tetrapeptide KARD. These and other peptidyl portions of CDKs can be tested for binding to CCR-proteins such as p15 or p16 using, for example, the thi