Creatine kinase isoenzyme patterns in normal smooth muscle and smooth muscle neoplasms.

The CK isoenzyme composition of leiomyoma tissue is predominantly CK-BB and similar to adjacent myometrium tissue, while the leiomyosarcoma revealed a lesser quantity of CK-BB, but a greater quantity of CK-MM. The reasons for the discrepancy between the two types of neoplasms is not clear, but may reflect the changes which occur when smooth muscle becomes malignant.