Regulation of normal cell cycle progression by flavin-containing oxidases

Mechanismsunderlyingtheroleofreactiveoxygenspecies(ROS)generatedbyflavin-containingoxidasesinregulat-ing cell cycle progression were examinedin human androdent fibroblasts. Incubation of confluent cell cultureswithnontoxic/nonclastogenicconcentrationsoftheflavo-protein inhibitor, diphenyleneiodonium (DPI), reducednicotinamideadeninedinucleotidephosphate(NAD(P)H)oxidase activity and basal ROS levels, but increasedproteolysis of cyclin D1, p21