B-myb co-immunoprecipitates with cyclin A1 in vivo.

U937 leukemic cells were lysed in RIPA buffer, and cyclin A1 was immunoprecipitated with rabbit polyclonal anticyclin A1 antibody. Polyclonal mouse IgG antibody served as a control. The Western blot was probed with anti–B-myb antibody. Besides the IgG band and 2 non-specific bands of similar strength in both lanes, 2 specific bands were seen that represent B-myb in its phosphorylated and non-phosphorylated forms (compare to Figure 7B).16