TSPO and glioblastoma: A detailed time response study by Costa et al. [40], applying the covalent TSPO ligand irDE-MPIGA to GBM cells, showed that it takes more than 90 min for irDE-MPIGA (25 nM) to irreversibly saturate all TSPO binding sites; 3 h after ligand application ΔΨm collapse was observed; 6 h after ligand application externalization of phosphatidylserine was observed and cell viability was reduced.