Hsp72 is a member of the Hsp70 family of molecular chaperones, and Hsp90 inhibitors upregulate its expression by activating the Hsf-1 transcription factor.34 Colon cancer cells depleted of Hsp72 (and a second Hsp70 isoform), apoptosed when exposed to AAG, whereas mock-depleted cells did not.35 Similarly, Hsf-1-null transformed fibroblasts were more responsive to AAG than were their wild-type counterparts.36 Whether SCH prevents the upregulation of Hsp72 by Hsp90 inhibitors in OS cells remains to be determined. The gene discussed is HSF1; the disease is malignant colon neoplasm.