In a groundbreaking study, Zeisberg et al. used three mouse models of renal fibrosis—UUO, a model for studying progressive tubulointerstitial fibrosis, streptozotocin (STZ)-induced DN, and alpha 3 chain of collagen type 4 (COL4A3) knockout mice—to confirm first the role of EndoMT in renal fibrosis [327]. This evidence concerns the gene COL4A3 and renal fibrosis.