GSK3B and fibrosis: To discover the mechanisms by which cyclin G2 influences tubulointerstitial fibrosis, we activated the Wnt signalling pathway using the GSK3β inhibitor CHIR99021.43, 44 Before CHIR99021 addition, cyclin G2 overexpression inhibited both the expression of proteins associated with Wnt signalling and tubular interstitial fibrosis.