NUDT1 and neoplasm: In all, 32 (38%) patients whose tumor specimens showed strong and diffuse MTH1 immunoreactivity were categorized in the high MTH1 expression group (Fig. 2B) and 52 (62%) patients whose tumors showed weak and focal MTH1 immunoreactivity (Fig. 2C) or immunoreactivity comparable to that of the surrounding matrix (Fig. 2D) were categorized in the low MTH1 expression group.