GRK2 and familial dilated cardiomyopathy: The results showed a significant increase in GRK2 expression in myocardial tissue of diabetic mice at 12 weeks of age along with increases of cardiomyocyte apoptosis and myocardial fibrosis and ventricular wall thickening, which can be considered as the early stage of DCM.27, 28 GRK3 and GRK5 were found in the left ventricular myocardium of mice, but there was no significant difference compared to nondiabetic controls at the corresponding age.