MYH7 and systolic heart failure: The Gata4fl/fl::Gata6fl/fl::Myh7-Cre mouse model was interpreted to show an essential role of these transcription factors in regulating adult heart systolic function; however, our data on inactivation of these genes in the adult heart suggest that the systolic heart failure phenotype was a result of abnormal heart development in the absence of these key transcriptional regulators.