Evaluating the effects of sulindac and piroxicam on cell kinetic parameters of two human colon cancer cell lines, HT-29, which expresses both COX-1 and COX-2 enzymes, and HCT-15, which is COX-null, it was shown that cell proliferation, cell cycle arrest, and apoptosis were independent of their inhibitory effect on PG synthesis [47]. Here, PTGS1 is linked to malignant colon neoplasm.