Specifically, transfection of the CD9 3′UTR construct into breast cancer cell lines resulted in lower luciferase activity than that observed in non-tumorigenic 184A1 cells (Figure 4D), suggesting that breast cancer cells have an increased amount of endogenous factors, such as miRNA, that reduce CD9 expression via acting at its 3′UTR. The gene discussed is CD9; the disease is breast carcinoma.