Irrespective of its role in drug-resistance, P-gp also plays a role in membrane depolarization (44), and it is thought that constitutive P-gp overexpression in MCD and brain tumors may explain their epileptogenic properties, and the conclusion was that ABC-transporters could help to better identify abnormal progenitor cells and serve as a biomarker of risk for seizure relapse after epilepsy surgery (44). This evidence concerns the gene ABCG2 and brain neoplasm.