GNAS and cancer: POH is a natural monoterpene found in several essential oils, and its antitumor activity has been well established in the literature and supported by in vitro and in vivo studies, and Phase II clinical trials in cancer patients.10 - 12 , 15 , 27 , 28 Recent studies have suggested that the POH also plays a role in the immunoinflammatory response.18 , 19