CDKN2B and renal fibrosis: found that miR-451a in hUCMSCs-Exo not only enhances the viability of HK-2 cells from DN mice and reduces their damage, but also downregulates α-SMA and upregulates E-cadherin expression, thereby helping to restart the blocked cell cycle, miR-451a can also inhibit the expression of P15 and P19 by targeting their 3′UTR regions, and reverse EMT both in vivo and in vitro, thereby inhibiting renal fibrosis (146).