Figure 7. Rac1 is activated by milk fat globule‐epidermal growth factor (MFG‐E8)–β1 engagement and is involved in MFG‐E8–mediated actin‐related protein 2 (Arp2) expression.

A, A10 vascular smooth muscle cells (VSMCs) incubated with either 50 μg/mL β1 inhibitory antibody (Itgb1 Ab) or isotype control 4 hours before treatment with either a low or high concentration of recombinant MFG‐E8 for 16 hours. Rac1 activity was measured using the G‐LISA (Cytoskeleton) assay. Data represent the averages of duplicate samples (n=2), and the error bars indicate the SD. *P<0.05, **P<0.01, ***P<0.001, as obtained using 1‐way ANOVA followed by Tukey multiple comparisons test. B and C, A10 cells were incubated with the Rac1 inhibitor NSC23766 (200 μM, Tocris) 16 hours before treatment with low and high doses of MFG‐E8 for 16 hours. B, Immunoblotting analysis of the Arp2 protein expression in A10 VSMCs was performed. C, Quantitative analysis of Arp2 normalized to GAPDH was performed (n=4). Data are presented as mean±SD. Four repeated experiments were performed. Each point is derived from each of the 4 repeated experiments. *P<0.05 and **P<0.01, as obtained using 1‐way ANOVA followed by Tukey multiple comparisons test.