PU-WS13 is an inhibitor of the heat shock protein family member and chaperone protein glucose-regulated protein 94 (GRP94; IC50 = 0.22 μM). It is selective for GRP94 over the chaperones Hsp90α, Hsp90β, and TRAP1 (IC50s = 27.3, 41.8, and 7.3 μM, respectively). PU-WS13 (0.5, 2.5, and 12.5 μM) induces apoptosis without increasing Hsp70 protein levels in HER2-overexpressing SK-BR-3, BT474, and MDA-MB-361 breast cancer cells. It also induces apoptosis and necrosis in multiple myeloma cells but does not induces cell death in pre-B leukemic cells.
