PTGS2 and brain disorder: For instance, radiotracers binding the cannabinoid receptor 2 (CB2) receptor [8, 9] and cyclooxygenase-2 (COX-2) [10, 11] have been validated in preclinical models of brain disease and generally showed a robust increase in binding associated with neuroinflammation, while the first results from human PET studies are encouraging [12, 13].