H2S Signals through VEGFR-PI3K-Rac1-Cofilin Figure 6. H2S signals through VEGFR-PI3K pathway to mediate the activation of Rac1 and to promote cell migration of HUVECs. Representative blots (A) and statistical analysis (B) showing the effects of NaHS (50 mM) treatment on the phosphorylation of Akt, cofilin and MAPKs including ERK, p38 and JNK. (C) The action of pharmacologic inhibiting on the increased phosphorylation of Akt, ERK and cofilin triggered by NaHS and the respective statistical data (D). (E) G-LISA assays measuring the effect of recombinant VEGF (10 ng/ml) and different chemical inhibitors, including SU5416, LY294002, U0126 and NSC23766, on the activation of Rac1. (F) Statistical data of transwell boyden chamber assay showing that the promotion effect of NaHS on endothelial cell migration was inhibited by SU5416, LY294002 and U0126. VEGFR inhibitor-SU5416 (5 mM), PI3K inhibitor- LY294002 (10 mM), MEK inhibitor- U0126 (10 mM), Rac1 inhibitor- NSC23766 (50 mM). Data represent the means 6 SE. *P,0.05. NS, not significant. doi:10.1371/journal.pone.0044590.g006 a rearrangement of the actin cytoskeleton. While actin remodeling has an important role in driving cell migration [25]. Actin polymerization promotes protrusions named lamellipodia in the front edges of the migrating cells [26]. In the present research, the formed lamellipodia induced by H2S probably initiated the movement of the human endothelial cell. Of all the signaling molecules that are involved in cell motility, Rho GTPases play a vital role in controlling actin dynamics [27]. Our evidence strongly demonstrates that Rac1 can be selectively PLOS ONE | www.plosone.org 9 September 2012 | Volume 7 | Issue 9 | e44590