Additionally, upon ABCB1 silencing, GBM cells presented a higher TMZ cytotoxic effect possibly due to an increase of TMZ intracellular concentration, as reported by others through genetic perturbations or by blocking ABCB1 activity with chemical inhibitors (e.g. PSC833, reversan, CP-100356, and elacridar)58–60. The gene discussed is ABCB1; the disease is glioblastoma.