Effect of 17-AAG on cell proliferation and Hsp90 client protein levels. (a) Western blot analysis showing depletion of Hsp90 client proteins total-Akt and c-Raf following 17-AAG treatment of MCF-7 cells for 48 hours. Actin was used as a loading control. (b) Results of WST-1 assay showing 17-AAG effects on MCF-7 cell proliferation over a 48-hour treatment period. 17-AAG, 17-allyamino-17-demethoxygeldanamycin; Hsp90, heat shock protein 90.