Moreover, changes in the densities of receptors and synaptic proteins have been reported in vivo. Mice lacking Shank1 have decreased expression of Homer and GKAP/SAPAP in hippocampal PSD fractions (Hung et al., 2008). Deletion of Shank2 exon 7 results in significantly increased expression of NMDAR subunits in the hippocampus and significantly increased expression of both NMDAR and AMPAR subunits as well as Shank3 in the striatum (Schmeisser et al., 2012). Deletion of Shank2 exons 6–7 also results in increased NMDAR subunit expression, but reduces NMDAR-associated signaling, as assessed by the proportion of phosphorylated CaMKII, ERK1/2, and p38 in whole brain lysates (Won et al., 2012).
