Meyer-Schwesinger et al. (2009) observed that the levels of ubiquitin-modifying enzyme ubiquitin C-terminal hydrolase-L1 in podocytes was increased in the biopsies of patients with membranous nephropathy, focal segmental glomerulosclerosis, and lupus nephritis IV. Tossidou et al. (2010) pointed out that the increased ubiquitination levels of podocytes could promote the internalization of slit diaphragm proteins nephrin, resulting in podocyte dedifferentiation, foot process fusion, and proteinuria. Here, NPHS1 is linked to focal segmental glomerulosclerosis.