As Tumour Growth Factor-β1 (TGF-β1) signalling was a biological process regulated by the differentially expressed miR-21-5p in our patients, we analysed the impact of TGF-β1, the major factor driving renal fibrosis in podocytes and podocyte-derived exosomes [18,19]. This evidence concerns the gene TGFB1 and renal fibrosis.