[Protein kinase activity and phosphorylation of endogenous proteins in the rat colonic mucosa during chemical carcinogenesis].

Treatment with a single dose of 21 mg/kg, of 1,2-dimethylhydrazine was followed by a significant decrease in the level of cAMP-dependent protein kinase (histone kinase) in rats' large bowel mucosa after 72 hrs. However, its level returned to basal value after 2 weeks, with casein kinase level remaining unchanged. Both carcinogen--induced tumors of the large bowel and adjacent mucosa showed a drop in protein (mol. wt.-50 kdalton) was enhanced in tumor considerably.