MOS and neoplasm: Further links between senescence and meiosis can be found in the signalling pathways of two prominent proto-oncogenes, mos and ras. As reported above, mos activation is induced by DNA- or microtubule-damaging agents in TP53-mutated somatic tumour cells of various origins in association with their illicit shift to tetraploidy [21,23,61,63,64].