MAPK3 and RASopathy: Immunoblotting results show that dysregulation on several phosphoproteins account for more than one RASopathy, including ERK1/2 (Thr202/185 and Tyr204/187), AKT1 (Thr308 and Ser473), MEK1 (Thr292) and RAF1 (Ser259), which are the most co-occurring studied proteins along the syndromes (Table 1).