Fig. 4.

Tyrosyl-phosphorylated PAK1 and FLNa are required for maximal PRL-induced membrane ruffling. A, M2 and A7 cell lines were cotransfected with GFP-PRLR and myc-tagged WT PAK1 or Y3F PAK1 mutant. Cells were treated as in Fig. 3. Filamentous actin was visualized by staining with Alexa Fluor 350 phalloidin, and the transfected cells were visualized by both GFP fluorescence for PRLR and staining with αmyc for PAK1. Arrows indicate ruffles, and asterisks denote transfected cells. Scale bar, 20 μm. B, Ruffling index as a number of ruffles per cell was counted. White bars represent A7 cells, and black bars represent M2 cells. Bars represent mean ± se. *, P < 0.05. Each experiment was repeated three times. n = 300 for each experimental condition.