E2F1 and neoplasm: Moreover, some researchers found that the rs35301225 polymorphism in miR-34a (ranked third in the WINMDA forecast list) is involved in the development of human colon cancer via downregulation of tumor-promoting gene E2F1 as a tumor suppressor, and the C/A single-nucleotide polymorphism of miR-34a promotes colon cancer cell proliferation via upregulating E2F1 [43].