Selective HIF-1 dimerization inhibitor. Blocks protein-protein interaction of recombinant HIF-1α, but not HIF-2α, with HIF-1β (IC50 = 1.3 μM). Inhibits hypoxia-induced HIF-1 activity, and decreases VEGF and CAIX expression in osteosarcoma and breast cancer cells in vitro. Also reduces tubularization of hypoxic HUVECs. MW (observed): 2559.1.