EGFR and colorectal neoplasm: Therefore, it is likely that COX-2 and EGFR signalling pathways are inversely related to each other in human colorectal tumor tissue and that tumor cells need only one of the signalling pathways for disease progression; a suggestion supported by our western blot results where tumor tissues with high COX-2 protein (74 kDa) content did not show EGFR protein expression at all.