PGP and brain cancer: To demonstrate the application of BBB-in-a-CUBE in drug testing, we designed a chip to contain a BBB-in-a-CUBE and a Glioblastoma-in-a-CUBE as a brain cancer model to test the permeability and effect of the chemotherapy drug Vincristine, based on the study of Tivnan et al. 29 that reported that inhibition of PGP and MRP1 transporters by Reversan increased the effect of vincristine, a PGP and MRP1 substrate5,7,60, on glioblastoma cell death.