KRAS activating mutations have been found to specifically activate the MAPK‐ERK signaling pathway in endothelial cells derived from arteriovenous malformations of the brain, indicated by the increased level of ERK1/2 phosphorylation in endothelial cells cultures with mutant KRAS. 11Moreover, a study from Al‐Olabi, et al. found that multiple mosaic‐activating variants in four genes including KRAS associated with the activated MAPK pathway would cause sporadic vascular malformations.12 Here, MAPK3 is linked to arteriovenous malformations of the brain.