Seeking to identify micropeptides involved in renal fibrosis, we used ribosome profiling to screen kidney tissue from Nos3−/− mice (which lack nitric oxide synthase 3 in endothelial cells) with STZ-induced DN — a model of progressive DN (16) — compared with age-matched, nondiabetic Nos3−/− control mice (Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/JCI178392DS1). The gene discussed is NOS3; the disease is renal fibrosis.