ERBB2 and neoplasm: To mimic a pro-oxidative environment, CAR T cells were pretreated with sublethal concentrations of H2O2 (25 or 100 μM) for 30 min prior to coincubation with HER2-expressing tumor cells; these H2O2 concentrations are above physiological ROS levels; however, higher concentrations of H2O2 are necessary to bypass cellular antioxidant capacity and induce sufficient global protein oxidation levels and are commonly used in redox studies (27, 28).