However, when the insult is severe and unresolvable, some cells fail to redifferentiate and continue to produce growth factors such as TGF-β, finally leading to renal fibrosis.119 Additionally, a recent study showed that TGF-βRII deletion in macrophages prevents tubulointerstitial fibrosis following severe ischemic renal injury by abrogating TGF-β-dependent chemoattraction of macrophages.118 Collectively, the functions of TGF-β/Smads may vary according to their activation level, disease stages, and types of AKI models, which need to be further validated. The gene discussed is TGFB1; the disease is renal fibrosis.