MIF and focal segmental glomerulosclerosis: In particular, we will present recent findings on the role of activated parietal epithelial cells (PECs) and the role of growth factors and their receptors from the platelet-derived growth factor (PDGF) family and macrophage migration inhibitory factor (MIF) for the development of renal tubulointerstitial fibrosis and focal segmental glomerularsclerosis (FSGS).