Macro creatine kinase type 2 in human colonic tissues.

Macro creatine kinase type 2 (MCK-2) is a promising new tumour marker for carcinoma of the colon. We have purified it from tumour tissue, from serum and, for the first time, from normal colonic epithelium and identified it in a tissue culture line of colon cancer cells. The molecular weight of each preparation, regardless of the source, was similar. Its consistent presence in tumours and in normal colon, contrasted to its variable appearance in serum, implies that there are other factors affecting its release into, or removal from, the circulation.