We also showed that normal human fibroblasts are resistant to 2-oxo-Ado up to 120 μM, and that a tumour-derived cell line, MOLT4, is highly sensitive to 2-oxo-Ado resulting in cell death at doses of 80–120 μM, while U2OS cells exhibited only growth arrest, suggesting increased expression of MTH1. Here, NUDT1 is linked to neoplasm.