OGG1 and colorectal carcinoma: For all three genes, ERCC1, OGG1 and RAI, a comparison of expression levels between normal colonic mucosa and lesions in all cases combined (adenomas and CRC) yielded significantly higher expression levels in lesions, 3.3-fold P = 0.005, 5.6-fold P < 3*10-5 and 7.7-fold P = 0.0005, respectively.