PGA2 is a naturally occurring prostaglandin in gorgonian corals where it may function in self defense. It is generally not present in mammals. PGA2 has low biological potency in most bioassays, but it does show some antiviral/antitumor activity.[1] At a 25 uM concentration, PGA2 blocks the cell cycle progression of NIH 3T3 cells at the G1 and G2/M phase .[2] It has also been shown to act as a vasodilator with natriuretic properties.[3]