Figure 3.

Effect of PI3K inhibitor wortmannin on ATRA-induced ERK phosphorylation. A549 cells were serum-starved for 18 h and treated or nontreated (NT) with 5 μM of ATRA at different times. Cells were preincubated for 1 h with 10 μM of wortmannin (Wm) alone or in combination with ATRA. The phosphorylated form of ERK and Akt and total proteins were detected by western blot using specific antibodies. The graph represents the densitometric analysis of ERK and Akt phosphorylation in three independent experiments (means ± SEM, ^* P < 0.05; ^** P < 0.001; analysis of variance and Newman-Keuls test).