Characterization of casein kinase II in human colonic carcinomas after heterotransplantation into nude mice.

Casein kinase II (CKII) activity in colorectal tumours was compared before and after heterotransplantation onto nude mice. The test revealed that the enzyme activity was about two-fold enhanced in the tumours isolated from the nude mice when compared to the respective primary tumours from which they were derived. Immunoblots using a polyclonal CKII-specific antibody showed that the increase of activity was due to a higher expression of the enzyme. Immunohistochemical studies on cross sections of nude mouse tumours showed that most of the CKII molecules were located at the peripheral part of the tumour; the central part did not show intense CKII-specific staining.