Suppression of Tax activity by wild-type p53 in cells containing Tax protein. Jurkat-Tax cells that constitutively express Tax and MT-2 cells were transiently transfected with HTLV-I LTR CAT reporter construct (5 μg) and expression vectors for wild-type p53, mutant p53s (143A, 248W, and 273H), or parental vector pCMV-NeoBam (5 μg). CAT activity was measured on cellular extracts prepared 48 hours after transfection.