(a) HEK-293T cells were transfected with p-CMV-Myc3-Mdm2 (2 µg) alone or with HA-Tat (1 µg). At 36 h post-transfection, the cells were treated with AKT inhibitor (4 µM) for 8 h. Total Mdm2 and phospho-Mdm2 (S166) levels were determined by western blot analysis. (b) HEK-293T cells were serum starved for 36 h and then incubated with the Tat protein (10 ng/ml) for 30 min before harvesting the cells. The cells were then subjected to western blot analysis with anti-AKT, anti-phospho-AKT (S473), anti-Mdm2 and anti-phospho-Mdm2 (S166) antibodies. Total AKT was used as a loading control. (c) Jurkat T cells were serum starved for 36 h and incubated with the Tat protein (10 ng/ml) for the indicated time periods. The cells were collected and subjected to western blot analysis with anti-AKT, anti-phospho-AKT (S473), anti-Mdm2 and anti-phospho-Mdm2 (S166) antibodies. Total AKT was used as a loading control. Bar diagrams represent the protein quantitation of respective western blots using Image J software. The results are representative of three independent experiments. P-values were calculated by a two-tailed t-test (*P < 0.05, **P < 0.01).