MAPK3 and neoplasm: In the four RGNT-like tumours analysed (except RGNT-4 due to lack of material), neurocytic regions showed strong and diffuse p-Erk1/2 staining, though p-Erk1/2 staining was relatively weaker and less in astrocytic regions compared with neurocytic regions (Fig. 3B and Supplementary Fig. 3).