HINT1 and neoplasm: Not only Hint1‐knockout (KO) mice but also Hint1‐heterozygous (HT) mice are more susceptible to induction of mammary and ovarian carcinogenesis by 7,12‐dimethylbenz[a]anthracene (DMBA) than wild‐type (WT) mice, which suggests that HINT1 is a haplo‐insufficient tumor suppressor (Li, Zhang, Su, Santella, & Weinstein, 2006).