Our results are in line with previous findings on the relationship between HIF‐1α and mitochondrial dysfunction.40, 41 It is known that ROS are mainly generated from complex III of the electron transport chain in the mitochondria, which are increased under hypoxic conditions.42 Activated HIF‐1α expression could prevent cancer cells from ROS‐induced apoptosis,43 while knockdown of HIF‐1α could induce cell apoptosis.17 In our study, we found that QL could decrease ROS production and caspase‐3 activity, increase the Bcl‐2/Bax ratio and inhibit cell apoptosis in a HIF‐1α‐dependent manner. The gene discussed is BCL2; the disease is cancer.