ABCC1 and glioblastoma: In another study [262], Tong et al. established a polyethyleneimine (PEI)-capped pSiNPs system to achieve high-capacity loading for delivery of siRNA, targeting to the gene of multidrug resistance-associated protein 1 (MRP1), an overexpressed chemoresistance-associated biomarker in glioblastoma multiforme (GBM).