CHIR-99021 (monohydrochloride) is Potent and selective inhibitor of the glycogen synthase kinase GSK-3. Promotes cell renewal in embryonic stem cells by modulating Notch, MAPK and TGF-β signalling pathways, which are involved in pluripotency. It also affects the Wnt/β-catenin pathway and alters expression of genes coding for proteins, epigenetic regulatory elements and non-coding RNAs. The combination of CHIR 99021 and basic fibroblast growth factor (bFGF) allows long-term self-renewal in adult mouse retinal progenitor cells.