FN1 and renal fibrosis: The epidermal growth factor receptor (EGFR) enhances the production of the key ECM components collagen I (COL I), collagen IV (COL IV), and fibronectin (FN) in GMCs, aggravating renal fibrosis and glomerulosclerosis in DKD (Uchiyama-Tanaka et al., 2002; Wu et al., 2009a; Wu et al., 2009b; Taniguchi et al., 2013).