In cancer cells, mitochondrial ROS can contribute oxidative stress to mitochondrial DNA (mtDNA), proteins and lipids, thus leading to hyperactivation of several signalling pathways from the mitochondria to the cytoplasm, such as NF-κB, MAPK, and HIF-1α, to promote the proliferation, angiogenesis and metastasis of tumours. The gene discussed is NFKB1; the disease is neoplasm.