FN1 and diabetic kidney disease: Moreover, the TGF-β secreted by inflammatory cells binds to TβR and plays a role in inflammation or fibrosis by transmitting to Ras (98, 99), MAPK (100), phosphatidylinositol 3-kinase (PI3K) (99, 100), serine/threonine protein kinase (AKT) (101), NF-κB (102), etc. Inhibition of the Klotho-dependent TGF-β1/p38MAPK pathway can reduce the levels of a-SMA and FN, increase the expression of E-cadherin, and inhibit the proliferation and fibrosis of abnormal renal cells in diabetic nephropathy (103).