PGP and amyotrophic lateral sclerosis: However, [11C]metoclopramide PET may still provide clinically useful information by allowing to assess the contribution of P-gp up-regulation to drug resistance in different forms of epilepsy as well as in various other brain diseases (e.g. multiple sclerosis, brain tumours, and amyotrophic lateral sclerosis), which may entail the change of medication to non-P-gp transported drugs.