Different than the 17-AAG therapy (Figure 3), the PFD treatment also decreases Hsp90 expression in total tumor lysates as observed in 293T cells (Figure 4B), indicating that it may inhibit the Hsp90 phosphorylation in tumors, which was confirmed by WB analysis of Hsp90 precipitates (Figure 6C/D). Here, HSP90AA1 is linked to neoplasm.