PRKG1 and Myocardial fibrosis: Musclin, a skeletal muscle derived and secreted myokine, attenuates cardiac dysfunction and myocardial fibrosis by augmenting the CNP/NPR-B stimulated crosstalk of cGMP to cAMP in cardiomyocytes and by inhibiting p38 MAPK signaling through the activation of PKG in cardiac fibroblasts.