A higher cytotoxicity of PF-00477736 was observed in a panel of MM cell lines displaying the t(11;14) as compared to those without the translocation and the inhibition of the CDK4/6 cyclin D1 complex activity, which in MCL cell lines is over-activated, partly neutralized the cytotoxic effect of the Chk1 inhibitor [24]. Here, CDK4 is linked to mantle cell lymphoma.