TP53 and breast cancer: However, the peptide can still kill cancer cells with elevated WT p53 (i.e., some breast cancer lines, see Table 1), levels similar to mutant p53 tumor cells with about 50% less efficacy than the same cell with equal amount of mutant p53 such as in PC-3 and H1299 null p53 cell lines with a stably transfected temperature sensitive mutant p53 (V143A) (data not shown).