MAPK1 and uvea neoplasm: Of note, strong immunoreactivity to pERK1/2 was readily detected in cutaneous tumours driven by the expression of oncogenic HRASG12V (Supplementary Figure S5C.V), indicating its capacity to maintain sustained ERK activation, which was barely evident in comparative GNAQQ209P-driven uveal tumours (Supplementary Figure S5D.V).