To assess the role of miRNAs in late development and postnatal heart, Chen et al. used a relatively late cardiac specific Cre line, MHCCre/+, to delete Dicer, and found that Dicer mutant mice suffered from severe dilated cardiomyopathy and heart failure, and died shortly after birth (Chen et al. 2008). This evidence concerns the gene DICER1 and dilated cardiomyopathy.