ME1 and cancer: ME1 metabolism is known to be regulated by well-known oncogenes or tumour suppressors such as K-ras, myc or p53.7, 13 Furthermore, ME1 is reported to be a potential prognostic or sensitivity marker of radio therapy.11, 12 Our immunocytochemis study revealed that ME1 localised in the cytosol, whereas ME2 and ME3 localised in the mitochondria, which is consistent with previous findings.8, 9 We found that ME1 is highly expressed in most cancer cell lines compared to ME2 and ME3, although some cell lines predominantly expressed ME2 or ME3.