Srf controls the expression of actin genes and genes implicated in actin cytoskeleton regulation. (A) Venn diagram showing the intersections between genes differentially regulated by Srf (P < 0.05) in MBs (D0), myocytes at onset of differentiation (D1), and differentiated cells (D3). In red is indicated the number of genes (144) that are modulated by Srf independently of the differentiation state. (B) Top five canonical pathways identified by gene ontology analysis using Ingenuity of the 144 common genes whose expression is Srf dependent. (C) Analysis of α-skeletal actin (Acta1), α-cardiac actin (Actc1), smooth muscle actin (Acta2), γ-actin (Actg), and β-actin (Actb) mRNA expression by qRT-PCR in FACS-sorted control and Srf mutant SCs cultured in rich medium (D0) or 1 (D1) and 3 (D3) days after differentiation. Data were normalized by Hmbs expression and relative to D0 (n = 3). (D) Analysis of Abra, Cnn2, Fermt2, FlnA, Tgfb1i1, and Wdr1 mRNA expression by qRT-PCR in FACS-sorted control and mutant SCs cultured in rich medium (D0) or 1 (D1) and 3 (D3) days after differentiation. Data were normalized by Hmbs expression and relative to D0 (n = 3). Data are mean ± SEM. *, P < 0.05; **, P < 0.01.