Several promoters such as carcinoembryonic antigen (CEA), cyclooxygenase-2 (COX-2) [18], human telomerase reverse transcriptase [19], and Urokinase-type plasminogen activator receptor (uPAR) [20] have been assayed to direct suicide genes into CRC cells. The gene discussed is PTGS2; the disease is colorectal carcinoma.