NPHS1 and glomerulosclerosis: Injury to podocytes commonly leads to proteinuria62 and glomerulosclerosis.62,63 Podocytes have VDR, which is markedly upregulatable,162,163 and the podocyte nucleus has a VDRE (vitamin D response element) in its DNA near the promoter start site for the nephrin gene.164 Calcitriol stimulates nephrin mRNA and protein;164 nephrin is an essential protein in the slit pore membrane of the glomerulus.