Figure 7

Akt activation promotes the down-regulation of RARβ2 and p53. (A) Left, A549 cells were transfected with Myr-Akt, Akt-K179M or empty vector and subsequently treated or non-treated with 5 μM of ATRA for 48 h. Total extracts were prepared and levels of protein were detected by western blot. Right, the graph shows the results of densitometric analysis of relative RARβ2 protein expression levels, obtained in three independent experiments (means ± SEM, *P < 0.05 compared with non-treated cells (NT) transfected with empty vector (analysis of variance and Newman-Keuls test). (B) A549 cells were transfected with Myr-Akt and subsequently treated or non-treated with 5 μM of ATRA for 48 h. For the last 24 h of the 48 h treatment period, the cells were incubated with 20 μM of MG132. Total extracts were prepared and levels of protein were detected by western blot using specific antibodies. The image shows one representative experiment of three independent. (C) A549 cells were serum-starved and treated or non-treated (control) with 5 μM of ATRA alone or in combination with 5 μM of 15e for 24 h. The proliferative effect was assessed by BrdU labeling according to the manufacturer’s instructions. The graph shows the results of three independent experiments (means ± SEM, *P < 0.05: **P < 0.001 compared with non-treated cells (NT) (analysis of variance and Newman-Keuls test).