ABCC5 and glioblastoma: A study performed in our institution investigated the expression of different multidrug resistance proteins (MDR) proteins on GBM specimens confirming the expression of P-glycoprotein-1 (Pgp-1) and multidrug resistance-associated protein (MRP)-1 proteins [6,7,8], but also finding the presence of MRP-3 (ABCC3) and MRP-5 (ABCC5) [9].