When ALK5 was knocked down (Fig. 7j), NEU1 overexpression-induced KIM1 (Fig. 7k) and ALK5-SMAD2/3 signaling pathway activation (Fig. 7l, m) were abolished in HK-2 cells, indicating that NEU1 promoted renal fibrosis in an ALK5-dependent manner. This evidence concerns the gene SMAD2 and renal fibrosis.