BGN and fibrosis: Even though, there are no data addressing biglycan and sphingolipid interaction directly, SphKs and S1P have been studied in several renal diseases associated with overexpression of biglycan [11,62,63,64], namely diabetic nephropathy [65,66], glomerulonephritis [67], fibrosis [68], nephroblastoma [67] and acute kidney injury [69,70].