 The process of electron transfer from NADPH to P450scc is not tightly coupled; that is, during electron transfer from adrenodoxin reductase via adrenodoxin to P450scc, a certain portion of the electrons leak outside of the chain and react with O2, generating superoxide radicals.Steroidogenic cells include a diverse array of antioxidant systems to cope with the radicals generated by the steroidogenic enzymes.In each steroidogenic cell, the expression of the P450scc system proteins is regulated by the trophic hormonal system specific for the cell type.