Recent studies have indicated that Egr1 plays a crucial role in the pathogenesis of renal fibrosis by activating the promoters of collagen 1α1 (COL1A1), cartilage oligomeric matrix protein (COMP), periostin, matrix metalloproteinase 2 (MMP2) [11], tissue metallopeptidase inhibitor 1 (TIMP1), and osteopontin (OPN). Here, SPP1 is linked to renal fibrosis.