We have been interested in the study of human cancer prevention, particularly in human colorectal cancer. There are several known cancer chemopreventive compounds, but non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin, ibuprofen, naproxen, etc., are the most well determined chemopreventive compounds in colorectal cancer. Many potential molecular mechanisms are proposed regarding their effects on anti-tumorigenesis, but apoptosis induction by these compounds is one mechanism to exert their anti-tumorigenic activity. We have found that NSAIDs induce several pro-apoptotic proteins, including NAG-1, ATF3, EGR-1, and other tumor suppressor proteins at the transcriptional level, and these proteins plays pivotal roles in NSAID-induced anti-tumorigenesis. The second groups of the chemopreventive compounds we have been interested in are PPARgamma ligands. These compounds are in use in clinics as anti-diabetic drugs; however, it has been also known that these drugs have an anti-cancer activity.  PPARgamma ligands increase the expression of NAG-1, EGR-1, and other tumor suppressor proteins in PPARgamma independent manner. The third compounds we are interested in are polyphenols found in our meals. Many food components from grape, soybean, green tea, cabbage, and broccoli possess anti-cancer activity. Indeed, epidemiological studies have suggested that nutrition plays an important role in carcinogenesis and dietary factors have been estimated to account for up to 80% of cancers of the gastrointestinal tract and approximately 30% of cancer morbidity and mortality might be prevented with proper adjustment of diets. We have found that several polyphenols increase tumor suppressor proteins at the transcriptional levels. We are expanding our research to other cancers such as prostate, breast, lung, and head and neck cancers, and our research will provide better rationale designing cancer chemopreventive compounds in the future.