In addition, He et al. also revealed firstly an interplay between HIF-1α and the autophagy−Zn2+−reactive oxygen species (ROS)−autophagy cycle axis and confirmed that ZnO NPs could up-regulate HIF-1α in osteosarcoma cells mainly due to the combined effect of Zn2+ and ROS (He et al., 2020). The gene discussed is HIF1A; the disease is osteosarcoma.