The selective cyclo-oxygenase 2 (COX-2) inhibitor, celecoxib (Celebrex, Pfizer Inc.), is being investigated as an anticancer agent in chemoprevention and adjuvant therapeutic regimens in many organ systems including the head and neck, lung, colon, breast and bladder. The mechanisms of action are not fully defined and, to date, there are no data regarding the shortterm molecular effects of celecoxib treatment in human tumor tissues. These data are important for understanding the targets and effects of COX-2 inhibitors in cancer.