Affinity for rat cerebrocortical TSPO and central-type benzodiazepine receptors (CBR), cytotoxicity against glioma cells and transport across Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCKII-MDR1) cells of MTX and TSPO ligand-MTX conjugates 3 and 4. The gene discussed is TSPO; the disease is central nervous system cancer.