Fig. 4. MEF2C/EnR expressed via an Nkx2-5 enhancer resulted in a thin-walled myocardium in type-II founder transgenic mouse embryos. Immunofluorescence was performed with anti-MyHC antibody MF20 (D,E,F) to indicate the cardiomyocytes in sections from wild-type (A,D), type-I (B,E) and type-II (C,F) transgenic embryos. Sections were stained with Hoechst dye 33258 to indicate nuclei (A-C).