APEX1 and glioblastoma: The uptake of PEG-DSPE-coated O-GNRs loaded with anti-tumor drug lucanthone (Figure 3), which is an endonuclease inhibitor of apurinic endonuclease-1 (APE-1), by glioblastoma multiforme (GBM) cell line U251 and APE-1-overexpressing U251 cell line exceeded 67% and 60%, respectively, post 24 h; cell death was necrotic, likely due to oxidative degradation of APE-1.