As shown in Figure 2(a), significant differences in median urinary APE1/Ref-1 levels were found between control (n = 108) and low-grade tumor groups (0.498 ± 0.035 ng/100 μL, n = 98; p < 0.01) and between control and high-grade tumor groups (0.982 ± 0.048 ng/100 μL, n = 71; p < 0.01). The gene discussed is APEX1; the disease is neoplasm.