FSTL1 and focal segmental glomerulosclerosis: By activating nuclear factor-kappa B (NF-κB) and wingless (Wnt)/β-catenin pathways, FSTL1 has been found to promote the progression of different forms of CKD, including focal segmental glomerular sclerosis(FSGS), membranous nephropathy (MN), immunoglobulin A (IgA) nephropathy (IgAN), etc. (19, 20).