MAPK1 and Intellectual disability: In addition to stimulating the AMPK pathway, reduced creatine uptake triggers the activation of the mitogen-activated protein kinase 1 (MAPK/ERK) pathway (Giusti et al., 2019), and disturbed ERK1/2 activity has already been linked to intellectual disability (Kalkman, 2012; Pucilowska et al., 2015, 2018; Borrie et al., 2017).