GAPDH and colorectal carcinoma: Normalization with respect to tissue weight is simple and accurate, compared to normalization based on the levels of the housekeeping genes B2M or GAPDH. The common over-expression of COX-2 in colorectal carcinoma suggests a role for COX-2 as a colorectal carcinoma risk biomarker, whereas attention should also be focussed on COX-2 inhibitors, as potential promising chemopreventive drugs for colorectal cancer.