They noticed that tadalafil improved the left ventricular function and prevented cardiomyocyte apoptosis in doxurubicin-induced cardiomyopathy through mechanisms involving up-regulation of cGMP, PKG activity, and mitochondrial superoxide dismutase level without interfering with the chemotherapeutic benefits of doxurubicin [14]. This evidence concerns the gene PRKG1 and cardiomyopathy.