The same factor can exert oncogenic or tumour-suppressive effects depending on cellular context—for example, METTL3 deletion in melanoma cells suppresses tumour progression and enhances CD8+ T cell infiltration 20, whereas METTL3 loss in macrophages promotes tumour growth and impairs PD-1 blockade efficacy 146. This evidence concerns the gene METTL3 and neoplasm.