Disruption of Cdk4 regulation by INK4 while c-myc is overexpressed in B-cells (in a c-myc-3'RR transgenic background prone to develop Burkitt lymphoma (BL)-like lymphomas [4]) leads to the development (in double mutant c-myc-3'RR/Cdk4R24C mice) of lymphoid malignancies closely resembling human MCL [5]. The gene discussed is MYC; the disease is lymphoma.