MAPK3 and RASopathy: RASopathy germline mutations have been identified in receptor tyrosine kinases, GTPases, RAS GTPase-activating proteins (RAS-GAPs), RAS guanine nucleotide exchange factors (RAS-GEFs), kinases, scaffolding/adaptor proteins, ubiquitin ligases, phosphatases and pathway inhibitors – with all identified mutations culminating in the activation of ERK1/2 (Tidyman and Rauen, 2016).