Differential distribution of nuclear cyclin D2 and cyclin D3 in Rag2^−/− pro–B cells but not MEFs. (A and C) Proliferating Rag2^−/− pro–B cells (A) or MEFs (C) were fixed, stained, and imaged for cyclin D3, cyclin D2, and Lamin B. Representative single plane confocal images are shown, with merged channel and transmitted light images provided. Bars, 5 µm. (B and D) Quantification of experiments in A and C shown as the mean ± SD derived from three independent experiments. (B) Percentage of detectable cyclin D3 colocalized with cyclin D2 (Manders’ coefficient). *, P < 0.01. (D) Percentage of cells scored positive for colocalization (at least 15% of cyclin D3 colocalized with cyclin D2). *, P < 0.001. (E and F) CDK4 immunoprecipitates and corresponding NP-40 TCLs from Rag2^−/− pro–B cells (E) or MEFs (F) were resolved by SDS-PAGE and membranes probed with the indicated antibodies. IP lanes: 8 × 10⁶ cells/sample; TCL lanes: 5 × 10⁵ cells/sample. Relative molecular mass (kD) is as indicated. Representative of three independent experiments.