ARRB2 and myocardial infarction: To exclude the affection of background expression of Arrb2 in WT mice, we transplanted WT or Arrb2 KO Sca-1+ CSCs to Arrb2 KO mice with myocardial infarction, high level of Arrb2 equal to better performance of cardiac function, including ejection fraction, cardiac output, stroke volume and Vmax (Table 2), which verified the important role of Arrb2 in heart repair.