Fig. 2. Stimulation of cardiomyogenesis of ES cells by H₂O₂. (A) ES-cell-derived embryoid bodies were treated on day 4 of differentiation with 500 nM H₂O₂ either in the presence and absence of the antioxidants vitamin E (100 µM) and NMPG (100 µM). H₂O₂ significantly increased the number of spontaneously contracting embryoid bodies on day 8 of cell culture, which was totally abolished in the presence of antioxidants. (B) Treatment of embryoid bodies with H₂O₂ significantly upregulated the cardiac-specific genes -actin, ANP, -MHC, MLC2a and MLC2v. (C) Upregulation of -actinin, MLC2a and cMLC1 protein by H₂O₂. The bar chart shows densitometric analyses of three independent experiments. ^*P<0.05, significantly different to the untreated control.