Interestingly, and as addressed in the section on aspirin pharmacodynamics, aspirin can alter the enzymatic activity of COX-2 through acetylation such that it generates precursors of aspirin-triggered forms (R-epimers) of lipoxins and resolvins that arise from these precursor molecules in transcellular processes of COX-2-expressing epithelial or cancer cells and polymorphonuclear leukocytes [151]. This evidence concerns the gene PTGS2 and cancer.