RAS encompasses two distinct pathways: the classical angiotensin II (Ang II)/ angiotensin II type 1 receptor (AT1R) axis, which promotes renal interstitial fibrosis, and the angiotensin converting enzyme 2 (ACE2)/ angiotensin (1-7) (Ang(1-7))/ G-protein-coupled Mas receptor (MasR) axis, which counteracts this process and delays renal fibrosis. The gene discussed is ACE2; the disease is renal fibrosis.