Figure 4.

StxB is able to activate p38α upon binding. (a) HeLa cells were starved for 2 h in HEPES medium before incubation with 250 ng/ml StxB for the indicated times. Cells were lysed, and cell lysate was passed through an anti-YP column. The eluate was then analyzed by Western immunoblotting with the indicated antibodies. One percent of the WCL was analyzed by SDS-PAGE and Western immunoblot to serve as control of equal loading on the column. (b) HeLa cells were incubated with increasing concentrations of StxB for 5 min at 37°C. Lysates were prepared and run for Western blot analysis by using the indicated antibodies. These experiments were repeated three times.