Manganese-superoxide dismutase is known to be particularly high in primary hepatoma (Taniguchi, 1992), gastric cancer (Taniguchi, 1992), acute myeloid and/or lymphocytic leukaemias (Nishiura et al, 1992), epithelial-type ovarian cancer (Ishikawa et al, 1990), central nervous system tumours (Cobbs et al, 1996) and neuroblastoma (Kawamura et al, 1992); on the other hand, lower SOD levels have generally been demonstrated in other tumour cells and clinical tumour tissues (Oberley and Buettner, 1979; Loven et al, 1984; Oberley and Oberley, 1988; Brorrello et al, 1993). Here, SOD2 is linked to lymphoid leukemia.