DRD4 and glioma: Dopamine receptor D4 (DRD4) on glioma cells activates the downstream effectors PDGFRB, extracellular signal-regulated kinase 1/2 (ERK1/2) and mammalian target of rapamycin (mTOR), thereby increasing glioma stemness and tumorigenesis.140 DRD4 inhibition disrupted the autophagy-lysosomal pathway, leading to the accumulation of autophagic vacuoles followed by G0/G1 arrest and apoptosis.140