Figure 2.

Maximal Invasion of TMX2–28 Cells in Response to PRL Requires Tyrosyl Phosphorylation of PAK1. A, TMX2–28 cells stably overexpressing GFP, PAK1 WT, or PAK1 Y3F were serum deprived, and equal amounts of cells were loaded into the upper part of the Boyden chamber coated with the Matrigel. The number of cells that migrated to the lower surface of the chamber toward PRL (100 ng/mL) (black bar) or buffer control (white bar) after 48 hours were counted in 5 random fields and plotted. B, TMX2–28 cells were transfected with control or PAK1 siRNA and assessed for invasion as in panel A. Silencing efficiency was judged by immunoblotting with anti-PAK1 Ab 48 and 72 hours after transfection. The expression levels of actin were used as an internal control. Bars represent mean ± SE. *, P < .05 compared with untreated cells. Each experiment was repeated three times. Scale bar, 300 μm.