PTGS2 and colorectal cancer: A series of cellular experiments demonstrated for the first time that oleanolic acid synergistically enhances aspirin to inhibit the proliferation and invasion of HCT116 and HT29 cells and induce S-phase arrest by regulating Akt/NFκB/IκBα/COX2 signaling pathway, thus synergistically enhancing the ability of aspirin to promote apoptosis of colorectal cancer cells.