Cytokeratin 18 (CK18) is cleaved by caspases during apoptosis and released into the bloodstream.16, 28 It has been recently reported that in the serum of SCCHN patients levels of CK18 and cleaved Caspase-3 were increased compared with that of normal healthy controls. The gene discussed is KRT18; the disease is head and neck squamous cell carcinoma.