Rb kinase activity of CDK immunoprecipitates during terminal erythroid differentiation.

Whole cell lysates from FVA erythroblasts (0, 24, 48 hours) (lanes 1-3), murine erythroleukemia (MEL) (lane 4), MB436 (lane 5), and Molt 4 (lane 6) cells were immunoprecipitated with antibodies to cdk6, cdk2, or cdk4. Immunoprecipitates were subjected to in vitro kinase assays using Rb as a substrate.