PTGS2 and colon carcinoma: Distinct metabolites of tocotrienols (T3s) have a positive impact on the development of colon carcinoma: δ-T3-13′-COOH, a naturally occurring constituent of the seeds of Garcinia kola, limited colon tumor cancer growth in mice, which was correlated with the inhibition of the tumor-promoting enzymes cyclooxygenase-2 (COX-2) and 5-LO, and ascribed to the regulation of autophagy caused by aberrant (dihydro)ceramide and sphingomyelin metabolism in cancer cells [22].