MAPT and glioblastoma: More interestingly, we measured a reduced metabolic activity of GBM cells for compound 1 with an IC50 value ranging between 4.2 ± 0.7 μM and 22.4 ± 5.2 μM among the Tau-expressing GBM cell models, against 33.2 ± 13.3 μM in Caco-2 cells not expressing Tau protein.