ABCC4 and glioblastoma: The most notable, and clinically relevant, finding presented in this publication, through the use of the MRP1 and MRP4 small molecule inhibitor, MK571, and also an MRP1 specific siRNA, is that MRP1 inhibition enhanced Vincristine- and Etoposide-, but not Temozolomide-induced cell death in primary or recurrent GBM cell lines.