Cask has been reported to be associated with X-linked mental retardation and autism-spectrum disorders.27,28 Cask is a multidomain scaffold protein that has been reported to mediate the anterograde transport of vesicles carrying N-methyl-d-aspartate receptor (NMDAR) subunits, particularly GluN1 and GluN2B, in neurons.29Cask expression in primary hippocampal neurons was reduced by FK866 treatment but restored by adding 100 μM NMN in the presence of FK866 (Fig. 5c). Here, GRIN2B is linked to autism spectrum disorder.