CTSK and coronary artery disorder: We also observed that tdT was expressed not only in skeletal muscle (muscle fibers and satellites) but also in smooth muscle in the artery, indicating a role of Ctsk in muscles and blood vessels; an increased serum level of CTSK was also observed in patients with coronary artery disease(50) and is involved in muscle degeneration and regeneration.(51) In addition, we defined two types of neural cells expressing tdT: pyramidal cells in the hippocampus and Purkinje neurons in the cerebellum.