PITX2 and familial dilated cardiomyopathy: In contrast, a comparative investigation of cardiac gene expression of RGS proteins in nonfailing donor hearts and in failing hearts from patients with DCM and ischemic cardiomyopathy identified differential expression of RGS proteins with preferential GAP activity toward Gi/o, including RGS2–5 of the R4 family and RGS6 of the R7 family (43).