There has been some dispute about the status of ERK activation in FXS though (mice: Hu et al., 2008; Gross et al., 2010; Osterweil et al., 2010; patients: Yrigollen et al., 2016), but pathway-specific inhibitors of ERK-signaling constantly rescued characteristic deficits in FXS models (Chuang et al., 2005; Osterweil et al., 2010; Wang X. et al., 2012), thus supporting the idea that enhanced mGluR1/5 cascades are causative for some symptoms of the disease. This evidence concerns the gene GRM1 and fragile X syndrome.