Antiangiogenic effects of hsp90 inhibiton. (A) 17-AAG abrogates VEGF + bFGF-induced endothelial cell proliferation. (B) 17-AAG (1 μM, 3-day incubation) suppresses the survival of human microvascular endothelial cells (HMVECs), as evidenced by MTT colorimetric survival assay. (C) 17-AAG (1 μM for 24 hours) suppresses the surface expression of IGF-1R in HMVECs. Filled curves correspond to staining with anti-IGF-1R antibody; open curves, staining with isotype control. (D) 17-AAG (500 nM for 24 hours) abrogates constitutive and IGF-1-induced VEGF production by MM cells. (E) 17-AAG suppresses the transcriptional activity of HIF-1α in primary MM cells. Error bars indicate SD.