Figure 4
ATRA stimulates Rac activation and promotes invasion. (A) Left, A549 cells were serum-starved for 18 h and treated with 5 μM of ATRA for the times indicated. Other cells were preincubated for 1 h with 5 μM of 15e. Activated Rac was detected with the Rac1 Activation assay kit according to the manufacturer’s instructions. Right, the graph shows the results of densitometric analysis of relative increase of Rac activation obtained in three independent experiments. (B) Cell invasion was analyzed by QCM™ 24–well Invasion Assay Kit. A549 cells were transfected with Myr-Akt, Akt-K179M or empty vector and seeded at 2.5 × 105 cells/well into the upper chamber. DMEM/F12 was added to the lower chamber with or without 5 μM ATRA for 48 h. The invasive cells were detected according to the manufacturer’s instructions. The graphs shows the results of three independent experiments (means ± SEM, *P < 0.05 compared with non-treated cells (NT) (analysis of variance and Newman-Keuls test).