Figure 9. Co-immunoprecipitation of B-Myb and PCNA. (A). QT6 cells were transfected with expression vectors for B-Myb, GFP-PCNA and Myc-Pdip1, as indicated at the bottom. Cell extracts prepared 16 h after transfection were then immunoprecipitated with antibodies against B-Myb. The immunoprecipitates and aliquots (5%) of the total-cell extract (TCE) were analyzed by western blotting with antibodies against B-Myb (top panels) or GFP (bottom panels). Protein bands corresponding to B-Myb and GFP-PCNA are marked. (B). Co-immunoprecipitation of endogenous B-Myb and PCNA. Cell extracts from untransfected Hek293 cells were precipitated with antibodies against PCNA or with control IgG, as indicated. The immunoprecipitates and aliquots (2.5%) of the total-cell extracts (TCE) were analyzed by western blotting with antibodies against B-Myb. The asterisk marks a non-specific protein band.