RhoGDIβ expression in H9c2 cells induces hypertrophic growth. (A) H9c2 cells stably transfected with empty vector (pTet) or pTet-RhoGDIβ were grown in 10% fetal bovine serum with doxycycline for 3 days. The transfected H9c2 cells were fixed and immunostained with rhodamine-conjugated phalloidin. (B) Relative cell size was measured after 3 days of growth of the transfected H9c2 cells in the presence of doxycycline. (C) Quantification of the cell size of H9c2 RhoGDIβ-expressing cells that also expressed RhoGDIβ siRNA (U6-353i or U6-568i) or scrambled siRNA (U6-Ci).