Phosphorylated p53ser15 doesn't interact with HIV-1 Tat protein. (A) ACH2 cells were transfected with FLAG-Tat and treated with 9AA or DMSO as a mock control. Expression of FLAG-Tat was detected by anti-FLAG (Sigma). Reactivation of p53ser15 was evaluated by anti-p53ser15 (Cell Signaling). (B) The cell lysates were then used for immunoprecipitation with anti-p53 or anti-p53ser15 (Cell Signaling). The immunopreciptated complexes were separated on 4–20% SDS-PAGE gels and then submitted to western blot to detect the presence of FLAG-Tat.