Differential effects of RhoAN19 and RhoAV14 overexpression on fiber stress formation induced by collagen I. (A) Migr-GFP⁺, Migr-RhoAV14-GFP⁺, and Migr-RhoAN19-GFP⁺ MKs were plated onto collagen I substrate for 1 hour on day 6, and cells were dually stained with a pMLC2 mAb (blue) and phalloidin-TRITC (red). Bars represent 5 μm. (B) The graph illustrates the mean percentage ± SD of Migr-GFP⁺, Migr-RhoAV14-GFP⁺, and Migr-RhoAN19-GFP⁺ MKs showing stress fibers after 1 hour of adhesion onto collagen I. At least 300 cells were counted in 3 separate experiments. Stress fiber assembly was induced in 30.7% MKs infected with the empty vector (Migr-GFP⁺), 42.7% Migr-RhoAV14-GFP⁺ MKs, and 20.4% MKs infected with Migr-RhoAN19-GFP⁺.