CDK4 and breast cancer: On the basis of these observations, we selected 4 cell lines in which CDK4 was likely dominant over CDK6 (JeKo-1, a mantle cell lymphoma line with cyclin D1 translocation, and CAMA-1, MCF-7 and T47D, which are HR-positive breast cancer cell lines) and 4 CDK6-dependent cell lines of hematopoietic or lymphoid origin (SEM, REH, MOLM-13, and Pfeiffer).