Figure 4.

The involvement of heat shot protein 90 (HSP90) in the proteasome inhibitor induced ErbB family degradation. Whole cell lysates of BT474 and SkBr3 cells treated for three days with various concentrations of bortezomib (A), 10 μM MG132, and 5 μM PSI (B) were subjected to western blot analysis with indicated antibodies. SkBr3 cells were transfected with siHSP90α and were then subjected to western blot analysis with indicated antibodies (C). The intensity of bands in western blot was quantitated using image J and β-actin/Tubulin was used as the loading control for normalization.