(A) WT cofilin-1, (B) Ad.S3A (constitutively active), or (C) Ad.S3E (phosphomimetic) infected neonatal cardiomyocytes. Adenoviral expression of the phosphomimetic cofilin-1 increases the formation of “stress-like” fibers (arrowheads). Red-fluorescence-protein reporter gene (RFP) indicates cardiomyocytes infected with Ad.WT, Ad.S3A or Ad.S3E, red; α-Sarcomeric Actin, green; phalloidin staining of F-actin, teal; nuclei stained with DAPI, blue. Other abbreviations as in Figure 2.