ABCG2 and glioblastoma: Concordantly, the pharmacological inhibition of the ABCG2 transporter with FTC, a recognized inhibitor of the ABCG2 transporting activity by allosteric binding to the protein, causing a conformational change that results in the impairment of ABCG2-mediated transport, significantly decreased the percentage of Fluo+ cells in all tested primary GBM cultures (Figure 5F,G).