THE CYCLIC ADENOSINE 3',5'-MONOPHOSPHATE-DEPENDENT PROTEIN-KINASE SYSTEM IN BREAST-CANCER

Components of the cyclic adenosine 3',5' monophosphate (AMP) dependent protein kinase system have been measured in primary tumours from 55 p atients with invasive breast cancer. There were highly significant pos itive correlations between levels of regulatory subunits as measured b y cyclic AMP binding proteins and catalytic kinase activity (both basa l and cyclic AMP-activated). This suggests that, in general, increased expression of binding proteins is accompanied by a corresponding elev ated level of catalytic activity. Nevertheless, individual tumours cou ld have substantially different proportions of regulatory and catalyti c activities. Whether such differences influence tumour behaviour rema ins to be determined.