(A) Effect of latrunculin B on MYXV growth. MDA-MB-231 cells were infected with the indicated viruses at MOI = 0.1. The media was replaced 8 h later with fresh media containing 0.1 µM latrunculin B (or the DMSO solvent control), cultured 48 h, and the resulting virus harvested and titered. (B) Effect of ROCK inhibitor Y-27632 on MYXV growth. MDA-MB-231 cells were infected with the indicated viruses at MOI = 0.1. Four hours later the media was replaced with fresh media containing 0 µM or 5 µM Y-27632, cultured 48h, and the resulting virus harvested and titered. (C) Effect on MYXV growth of siRNA silencing of RhoA, RhoC, mDia1 or LIMK2. MDA-MB-231 cells were transfected with the indicated siRNAs for 48 h, and then infected with virus at MOI = 0.1. The viruses were harvested and titered 48 h later. For each siRNA treatment, we report the yield of virus measured relative to the amount of virus produced in cells that were transfected in parallel with a non-targeting AllStars siRNA control. (D–F) Western-blot analysis of proteins extracted from siRNA-treated cells. MDA-MB-231 cells were transfected with the indicated siRNAs and cultured for 48 h. The cells were then harvested, lysed, and western blotted using antibodies directed against RhoA and RhoC (Panel D), mDia1 (E), and LIMK2 (F). β-actin was used as a loading control.