MAPK1 and Costello syndrome: In the Costello syndrome and neurofibromatosis type 1 models, it has been shown that besides the blockade of MAPK/ERK pathways, the inhibition of the downstream Notch cascade, either separately or collectively with MAPK/ERK, improved the myelin structure (Lopez-Juarez et al., 2017; Titus et al., 2017).