TPR and cancer: As shown in Figure 2(A), the Antp-TPR peptide caused a concentration-dependent loss of human cancer cell viability (in the Caki-1, BXPC3, T47D, and A549 cell lines); however, identical concentrations of this peptide did not apparently reduce the viability of normal human cell lines (HEK293T, MRC5, and PE) (Figure 2A), and TPR peptide without Antp, the cell-permeable peptide, had no effect on normal or cancer cells (Figure 2B).