HIF1A and neoplasm: The tumor showed 50.3% less tissue hypoxia, 49.3% decrease in expression of HIF-1α, and 31.8% decrease in VEGF expression 4 days after intravenous treatment with 13.2 mg/kg Man-HA-MnO2 NPs compared to those in the saline treatment group, indicating the ability of Man-HA-MnO2 NP to reduce tumor hypoxia.