GRK2 and heart failure: In addition, increased RKIP expression levels are a sufficient single cause of cardiac dysfunction in Tg-RKIP mice, which finally culminates in overt heart failure symptoms with dilative cardiomyopathy, increased levels of natriuretic peptides and Ace and Grk2 upregulation as indicators of an overactivated RAAS (renin angiotensin aldosterone system) and sympathetic nervous system.