GSK3B and amyotrophic lateral sclerosis: More recently, two other proteins involved in ALS have been identified as modulators of this interaction: glycogen synthase kinase-3β (GSK3β), established as a negative regulator of VAPB/PTPIP51 interactions, and TAR DNA-binding protein 43 (TDP43), which activates GSK3β [97] (Figs. 2, 4).