RB1 and colonic neoplasm: Reduced phosphorylation at Ser 608 and Ser 780 residues has been reported in colon cancer cell lines treated with CYC202 (R-roscovitine) which is a potent CDK2-cyclin E inhibitor and these cells undergo cell cycle arrest [22] and our data on the reduced phosphorylation of pRb at these sites in Na-Bu and BAY 61-3606 treated samples is in agreement with these results (Figure 3a–c).