[Presence of various protein kinases and of partially copurified endogenous substrates in the soluble fraction of an experimental tumor of the rat thyroid gland].

Various fractions containing protein-kinases have been partly purified from supernatant (105 000 g) of an experimental rat's thyroid cancer (1-8 Wollman). These fractions are activated at different levels by cyclic nucleotides and present an unequal affinity for protamine; they phosphorylate an endogenous substrate apparently copurified with the enzyme fractions and adorbed with them on calcium phosphate gel.