Protein phosphorylation in normal and neoplastic development. Cyclic AMP-dependent protein kinase activity in urethane-induced pulmonary tumours.

The cyclic AMP-dependent protein kinase specific activities of cytosol fractions from urethane-induced lung tumours and from normal mouse lung were determined. Both basal and cyclic AMP-stimulated activities in tumours were twofold higher than those of normal lung. Since neonatal and adult lung cytosols have identical kinase activities, the high activity in tumours appears to be a tumour-specific property.