17-DMAG is a water soluble & cell-permeable analog of Geldanamycin and 17-AAG (1). It binds to the APTase site of human Hsp90a with high affinity, has cytotoxic activity against many cancer cell lines (2), and acts as angiogenesis inhibitor (3). This Hsp90 inhibitor shows promise in preclinical models. 17-DMAG has excellent bioavailability, is widely distributed to tissues, and is quantitatively metabolized much less than is 17-AAG. It clears alpha-synuclein aggregates by inducton of autophagy (4).