MAPK1 and adenocarcinoma: The inactivation of ERK1 and ERK2 isoform phosphorylation in the early phase of colon tumorigenesis, refs. [19,20,21] with subsequent increased phosphorylation of ERK5 [22], is an intriguing phenomenon proposing an inhibitory function for ERK1/2 in the initial phases of adenocarcinoma development.