Transplasma membrane redox stimulates HeLa cell growth

Impermeable ferricyanide stimulates the growth of HeLa cells in absence of fetal bovine serum or other growth factors. A series of impermeable oxidants with redox potentials down to -125 mV stimulate equivalent growth. All of these oxidants are reduced by the transplasma membrane electron transport system. Oxidants with redox potentials below -175 mV are not reduced by the transmembrane electron transport and do not stimulate growth. Insulin which stimulates growth in absence of serum also stimulates transmembrane ferricyanide reduction. Ferricyanide increases growth in presence of insulin. Antitumor drugs, which inhibit HeLa cell growth, inhibit the transplasma membrane redox system. Transplasma membrane electron transport is accompanied by proton release from HeLa cells.