DL-TBOA is a competitive, non-transportable blocker of excitatory amino acid transporters (IC50 values are 6 μM, 6 μM and 70 μM, for EAAT2, EAAT3 and EAAT1, respectively). DL-TBOA also inhibits EAAT4 and EAAT5 (Ki values are 4.4 μM and 3.2 μM respectively). DL-TBOA displays high selectivity for EAATs over ionotropic and metabotropic glutamate receptors. In [3H]-d-Asp uptake assays in HEK293 cells expressing human EAAT2, EAAT1 and EAAT3, Ki values are 2.2, 2.9, and 9.3 μM, respectively. In a FLIPR Membrane Potential (FMP) assay, Km values are 0.59, 1.8 and 2.8 μM for human EAAT2, EAAT3 and EAAT1, respectively. DL-TBOA augments SN 38 (Cat. No. 2684) induced colorectal cancer cell death in drug-resistant cell lines. DL-TBOA enhances synaptic activity in the frog labyrinth.