Glycogen synthase kinase 3β (GSK3β) is a constitutively active serine/threonine protein kinase implicated in several important regulatory processes. It can phosphorylate β-catenin, an intracellular signal transducer in the Wnt signaling pathway, which leads to β-catenin degradation. IM-12 is a non-symmetrically substituted indolylmaleimide that increases β-catenin levels by inhibiting GSK3β (IC50 = 53 nM). It has been shown to reduce proliferation and increase differentiation of a ReNCell VM cell line derived from human ventral midbrain. IM-12 is also reported to have a depolymerizing effect on in vitro tubulin assembly.