text:  G4D_Sham_Rep2 Cardiacmyocyte This allele contains a deletion of the second coding exon of Gata4, including the start codon and the Nterminal 46% of the coding region. The mice used in this study were all male and on a uniform F1 genetic background resulting from the cross of Gata4WT/Δex2 (abbreviated; G4D) mice, backcrossed for greater than 8 generations into C57BL6/J, to wild-type FVB/N mice. G4D progeny from this cross were present at weaning at the expected Mendelian ratio (104/218, 48%), survived normally to 18 months of age, and had no evidence of structural heart disease (0 out of 15 embryos examined histologically at E15.5-E18.5). Gata4WT/WT littermates (WT) from these crosses were used as controls.