CDKN2A and cancer: We examined the DNA methylation levels of SFRP1, SFRP2, SFRP5, DKK2, DKK3, mir34b/c, RASSF1A, IGFBP7, CDKN2A, and MLH1 in normal colonic crypts isolated from regions that were adjacent to the cancer, as well as distal and proximal regions (left and right sides).