Pre/pro-B-cell lines were generated from bone marrow cells of Cdk6-/- mice by retroviral overexpression of the BCR-ABL (p185) fusion oncogene. These cell lines were transduced with constructs expressing HA-tagged versions of wildtype Cdk6 or of a C-terminally truncated variant of Cdk6 (HA-Cdk6-ΔC). Given the role of CDK6 in transcriptional regulation, we studied the phosphorylation of proteins associated with the chromatin (the phosphochromatome) using phospho-proteomics in cell lines that expressed C-terminally truncated CDK6, wildtype CDK6, or that had a CDK6 knock-out.