CCN1 and acute kidney injury: Cyr61 is a secreted heparin-binding protein that may possibly be involved in tissue growth and repair,50,51 which was originally described as a growth factor-inducible immediate early gene in fibroblasts.52 It was identified by Muramatsu et al. in 2002 by representational difference analysis as one of the genes that was rapidly induced following ischemia in rodent models of ischemic/reperfusion injury.53 The urinary levels of Cyr61 in rodents could be detected as early as three to six hours following renal injury, where it might eventually serve as an early biomarker of ARF.