AR and neoplasm: Alternatively, when β2- adrenergic receptor (AR) knockout (KO) mice were used, or if wildtype (WT) mice housed at 22 °C were given the pan-β-AR blocker propranolol, we observed a similar improvement in tumor growth control and increased CD8+ T cell infiltration was seen in mice housed at 30 °C22,29,34, suggesting that cool housing-induced adrenergic stress exerts its negative effects on the anti-tumor immune system through activation of β-ARs on immune cells.