FIGURE 3.

Overexpression of HEXIM1 stabilizes and activates p53. A, HEXIM1-transfected MCF7 cells were treated with or without UV. Cells transfected with an empty vector were used as the negative control. Expression of p53 and HEXIM1 proteins was analyzed by immunoblotting. Actin was used as the loading control. B, mRNA levels of p53 in the HEXIM1-transfected cells were measured by QRT-PCR. The cells transfected with an empty plasmid were used as a control. C, cell lysates prepared from the mock- and HEXIM1-transfected MCF7 cells were analyzed by IP. MG132 was added into the culture before harvesting. IP with a normal IgG was used as a negative control to exhibit the nonspecific background bindings. D, effects of HEXIM1 overexpression on the phosphorylation of p53 and the expression of p53 downstream targets were analyzed by Western blotting. Actin and p27 were used as controls.