TPR and cancer: It was also observed that the cytotoxic activity of both Antp-TPR alone and Antp-TPR in the presence of R11-Hsp70 toward normal mammary epithelial cells (MCF-10A) was less than that of these peptides against cancer cell lines, and that R11-Hsp70 did not affect the cytotoxic activity of 17-AAG (Additional file 1C).