Quercetin treatment up-regulated LC3B-II/LC3B-I and down-regulated P62/SQSTM1 expression, suggesting that quercetin increased autophagic flux in MG-63 cells. Specifically, quercetin induced osteosarcoma cell death by inducing excessive autophagy mediated by the ROS-NUPR1 pathway. The gene discussed is SQSTM1; the disease is osteosarcoma.