Recently, the mitochondrial-localized adenylate kinase 4 (AK4) has been shown to augment intracellular ROS production to promote HIF-1α stability, and by extension HIF-1 signaling, in the context of macrophages, breast cancer, and lung adenocarcinoma (LUAD) [13,14,37]. The gene discussed is HIF1A; the disease is breast cancer.