We have previously reported that CYP2J2 stimulates proliferation of carcinoma cells and protects human carcinoma cells from apoptosis [10]; so it was of interest to evaluate the effects of overexpression of let-7b on cell proliferation and apoptosis when endogenous CYP2J2 was inhibited by let-7b. This evidence concerns the gene CYP2J2 and carcinoma.