Increased phosphorylation of nuclear phosphoproteins in precancerous liver

An increase in the rate of phosphorylation of nuclear phosphoproteins, as measured by the in vitro transfer of ³²P from [γ-³²P]ATP into isolated nuclei, was observed in nuclei derived from livers of animals fed on a diet containing 3' methyl 4 dimethylaminoazobenzene compared with those from normal livers. The increase in the phosphorylation of nuclear phosphoproteins occurred in the early hyperplastic response prior to the formation of hepatoma.