Figure 4

Cdk2 relocalization to the cytoplasm correlates with increased binding to cytoplasmic p21 and p27. (a) Crude MDA-MB-231 cytoplasmic (C) or nuclear (N) extracts (Crude ext.) from cells treated as in Fig. 1 were subjected to immunoblot (IB) analysis with antibodies specific for Cdk2, p27, or p21 (top panel), or immunoprecipitated with a Cdk2 antibody or antibody from preimmune rabbit IgG (Rab. IgG), and the immunoprecipitates (Cdk2 IP) were probed with antibodies specific for Cdk2, p27, or p21 (bottom panel). (b) NMuMG cytoplasmic or nuclear extracts from cells treated as in Fig. 1 were subjected to immunoprecipitation with Cdk2 antibody or preimmune rabbit IgG, and the immunoprecipitates were probed with antibodies specific for Cdk2, Cdk2 phosphorylated on Tyr¹⁵ (P-Tyr15–Cdk2), Cdk2 phosphorylated on Thr¹⁶⁰ (P-Thr160-Cdk2), p27, or p21. Cont., control; Rapa., 100 nM rapamycin; T + R, 10 ng/ml transforming growth factor-β1 plus 100 nM rapamycin. LC, immunoglobulin light chain; HC, immunoglobulin heavy chain.