It changes a putative stimulatory protein (Sp1) binding site in the promoter of COX-2 between-766 and-761 bp [93], but it creates an E2 promoter factor (E2F) binding site, leading to high transcription activity, which may be the mechanism of COX-2-765G>C polymorphism increasing cancer risk [15]. Here, PTGS2 is linked to cancer.