Neurotensin also plays a role in peripheral tissues outside of the nervous system, mainly in the gastrointestinal tract, and has been implicated in cancer development. DNA promoter methylation has been shown to be a major regulator in the expression of neurotensin receptor 1 and 2 genes in colorectal cancer cells. Additionally, knock-down of the NTSR1 gene as well as treatment with a NTSR1 antagonist inhibited colorectal cancer cell proliferation and migration. Leiomyomas or fibroid tumors in uterine tissue have also been associated with higher expression of neurotensin and NTSR1.