In an interesting study done with glioma-bearing mice, where mice were housed either under standard conditions or in enriched conditions mice in larger numbers, in cages with toys, it was found that the environmental cues induced the activity of phagocytic macrophages in the TME by brain-derived neurotrophic factor (BDNF) and pro-inflammatory cytokines by NK cells [148]. The gene discussed is BDNF; the disease is central nervous system cancer.