Human colon tumors: enzymic and histological characteristics

In samples of colonic adenocarcinomas, the mean activities of thymidine kinase, glucose-6-phosphate dehydrogenase, phosphoserine phosphatase and pyrroline-5-carboxylate reductase were several fold higher than those of nonneoplastic colon. The presence of considerable, cold labile pyrroline-5-carboxylate reductase activity provided an additional criterion for distinguishing tumors from the control tissue. Deviations from the pattern of enzymes in normal colon were much more pronounced in the five moderately well-differentiated than in the single well-differentiated adenocarcinoma.