Protein kinase activity in mouse mammary carcinoma.

C3H mouse mammary carcinoma contains cyclic AMP-independent (C) and dependent (RC) protein kinases and a specific cyclic AMP-binding protein (R). The specific activities of C, RC and R are markedly lower in carcinoma than the normal mammary cells. Protein kinase preparation from neoplastic cells showed markedly higher ration of $\text{C}\text{RC}$ and lower responsiveness to cyclic AMP for the activation of the enzyme than the normal cells.