MAPK3 and neoplasm: Immunohistochemical analysis demonstrated nuclear accumulation of phosphorylated ERK1/2 (Fig. 3d), increased expression of c-MYC and increased abundance of γH2AX in AKrasfl/G12D tumours when compared to AKras+/G12D tumours, suggestive of MAPK pathway activation, increased cellular proliferation and activation of DNA damage response pathways (Fig. 3e, f).