In order to investigate whether CK20 expression, a known surrogate marker for the presence of CTCs in patients with colorectal cancer [26], can also be detected in blood and bone marrow samples of EC patients, a nested CK20 RT-PCR was performed with cDNA prepared from 74 blood and 61 bone marrow samples of 77 EC patients. The gene discussed is KRT20; the disease is colorectal cancer.