Hsp90 inhibition by PU-H71 induces apoptosis through endoplasmic reticulum stress and mitochondrial pathway in cancer cells and overcomes the resistance conferred by Bcl-2

► Hsp90 inhibition by PU-H71 induces ER-stress mediated apoptosis in human cancer cells. ► Apoptosis occurs through the mitochondrial pathway and requires Bax. ► PU-H71 exerts no toxicity toward healthy cells. ► PU-H71 overcomes Bcl-2 mediated resistance to apoptosis. ► Combination of PU-H71 and alkylating agents sensitizes resistant cells to apoptosis.