Water-soluble analog of 17-AAG (Cat. No. 1515) and geldanamycin (Cat. No. 1368). Binds the ATP binding site of Hsp90 and inhibits its chaperone activity. Displays more potent antitumor activity than 17-AAG (mean GI50 values are 53 and 123 nM for 17-DMAG and 17-AAG respectively).