MAPK1 and RASopathy: Two years ago, nearly 20 years from the discovery of PTPN11 as the first gene implicated in NS, the mitogen‐activated protein kinase 1 gene (MAPK1, MIM: 176948), also known as extracellular signal‐regulated protein kinase 2 (ERK2), encoding the terminal tier of the MAPK cascade, joined the group of the signal transducers mutated in the RASopathies.