KW-2478 is an inhibitor of Hsp90, with an IC50 of 3.8 nM for Hsp90α. KW-2478 shows anti-proliferative activity against multiple myeloma (MM) and non-Hodgkin’s lymphoma (NHL), with GI50s of 0.30 μM (OPM-2/GFP), 0.34 μM (KMS-11), 0.39 μM (RPMI 8226), 0.12 μM (NCI-H929), 0.36 μM (Raji), 0.098 μM (SR), and 0.33 μM μM (SC-1). KW-2478 also inhibits the transcription of c-Maf and Cyclin D1 genes by mainly suppressing the function of Cdk9.