PGP and breast carcinoma: Chavanpatil et al. used alginate particles ranging in size from 500 to 700 nm with the Aerosol OT® surfactant to deliver doxorubicin to drug-resistant human breast cancer cells NCI-ADR/RES (MCF-7/ADR) and to drug-sensitive human breast cancer cells MCF-7, which overexpress P-glycoprotein (Pgp), which play the “gatekeeper” role in BBB.The authors used primary bovine brain microvessel endothelial cells (BBMECs) for a normal Pgp-overexpressing control.