FN1 and glomerulosclerosis: In order to better assess the effect of the VD/VDR signaling pathway in the kidney, after overexpression of VDR in podocyte-specific knockout VDR (VDR-KO) mice, the albuminuria was significantly reduced, accompanied with some improved symptoms compared with VDR-KO mice, such as the disappearance of podocyte foot processes, the glomerular basement membrane (GBM) thickening, glomerular sclerosis, an increase in glomerular fibronectin levels, and a decrease of nephrin expression.