NTHL1 and cancer: Compared to sporadic breast cancers, NTHL1-het cancers as a group showed a 51% reduction in NTHL1 staining in the AE1/AE3-positive cancer cells (average staining intensity 24.51 vs. 49.83, P < 0.001 by unpaired t test) (Fig. 2a, b) and a 40% reduction in the AE1/AE3-negative non-cancer cells (35.62 vs. 59.65, P < 0.001).