However, curcumin reveals its antifibrotic effect at the activation stage of renal fibrosis by reducing TGF/Smad, MAPK/ERK, and sphingosine kinase 1 (Sphk1)/sphingosine-1-phosphate (S1P), as well as increasing PPARγ pathways to block fibrosis. This evidence concerns the gene SPHK1 and renal fibrosis.