Publications from the end of 1996 are discussed. They demonstrate that the gene encoding COX-2 cyclooxygenase (responsible for transformation of arachidonic acid to prostaglandins) undergoes high overexpression as early and central event of carcinogenesis in the colon and appears shortly after mutation of the second allele of the APC gene. The data points out that high COX-2 overexpression is common in epithelial neoplasms. Another recent important finding is also discussed. It demonstrates that the HER-2 gene activates COX-2 gene expression in large bowel cancer cells which enhances proliferation of the cells and increases their metastatic potential.