TWS119 is a GSK-3β inhibitor with IC50 of 30 nM; capable of inducing neuronal differentiation and may be useful to stem cell biology.

Glycogen synthase kinase 3 (GSK3) is a serine/threonine protein kinase that is inhibited by a number of extracellular stimuli such as insulin, growth factors, cell specification factors, and cell adhesion. Its activity regulates many cell functions including cell division, apoptosis, and inflammation. TWS119 is a 4,6 disubstituted pyrrolopyrimidine that potently inhibits GSK3β with an IC50 value of 30 nM.At 400 nM, TWS119 induces neurogenesis in mouse embryonic stem cells making it a useful tool to regulate stem cell self-renewal and differentiation.