ABCB1 and glioblastoma: Our study systematically assesses the CHR–TMZ combination in 2D and 3D U-87MG glioblastoma models, examining apoptosis, autophagy, mitochondrial membrane potential (MtMP), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT), cancer stem cell (CSC) markers, multidrug resistance (MDR) proteins, and nuclear factor-kappaB (NF-κB)/P-glycoprotein (P-gp/ABCB1) signaling using experimental and bioinformatic methods.