TSPO and central nervous system cancer: In detail, reversible and irreversible fluorescent probes featuring the 7-nitrobenz-2-oxa-1,3-diazol-4-yl group (18c,d) were synthesized, characterized for their optical properties and tested in spectroscopy experiments to evaluate their ability to specifically label the mitochondrial localization of TSPO in Drosophila S2, rat C6 and human U87MG glioma cells [70,71,72].