Radiolabelled GIP was additionally found to cross the BBB in a time-dependent saturable manner, which was inhibited by competition with native unlabelled GIP (26), suggesting involvement of a receptor-mediated mechanism, and GIP has been detected in the CSF of mice (47) and humans (154), which is interesting in the context of reported evidence of a neuroprotective effect of GIP in animal models for Alzheimer’s and Parkinson’s disease (16, 155). The gene discussed is GIP; the disease is Parkinson disease.