Fig. 2.

Mena associates with activated Rac1, and loss of Mena in cardiomyocytes significantly increases Rac1 activity. A: cardiomyocytes were incubated with GST-Pak1-p21 binding domain (PBD) or glutathione-S-transferase (GST) alone. After pulldown, active Rac1 (GTP bound) was detected by immunoblotting. Active Rac1 interacts with PBD domain of Pak1 and is absent in GST alone control lane. Mena is detected simultaneously in the same blot in Rac1-GTP lane. Whole input lysate was probed for total Rac1 (t-Rac1) and Mena. B: representative immunoblot is shown for Rac1-GTP, endogenous t-Rac1, Mena, and GAPDH in whole lysates. Lysates were subjected to GST-Pak1-PBD pulldown and SDS-PAGE gel electrophoresis. C and D: densitometry data is summarized for Mena (C) and Rac1-GTP (D). *P ≤ 0.05, **P ≤ 0.01 vs. SCR; n = 5, MenasiRNA transfection efficiency was 65%.