Our results show: (1) wild-type p53 stimulates the transcription of reporter genes with p53CON and RGC in their 5' region while most p53 mutants occurring in human cancers have lost this activity; (2) the R273H mutant retains transcriptional activity for the p53CON sequence but not RGC; (3) some mutants are temperature-sensitive for the transcriptional activity with the p53CON but not the RGC sequence; (4) p53 mutants vary in their ability to inhibit wild-type p53 transactivation but there is no difference between p53CON and RGC sequences; (5) lung cancer cells with endogenous mutant p53 proteins (M246I in H23 cells and R248L in H322 cells) retain transcriptional activity for the p53CON but not the RGC sequence.