Fig. 7. BOB.1/OBF.1 becomes degraded in a proteasome-dependent manner. (A) NIH 3T3 cells were transfected with BOB.1/OBF.1 expression plasmid alone or together with SIAH1 expression plasmid. Eight hours later, the proteasome inhibitor MG132 was added. (B) Ramos B cells were incubated with anti-IgM antibodies and MG132 as indicated. After 12 h the cells were harvested and analyzed by western blotting with appropriate antibodies. (C) Thirty minutes before Ramos B cells were incubated with anti-IgM antibody, the MAPK inhibitor PD98059 was added (25 µM). Twelve hours later the cells were harvested and analyzed by western blotting.