KRT20 and colorectal carcinoma: Our recent work has overcome this limitation by blocking the Fc region of the anti-BerEP4 antibody with a goat anti-mouse antibody during IE, so that an anti-CK20 antibody can be used to show the gastrointestinal (GI) origin of the BerEP4-positive cells in the blood of colorectal cancer (CRC) patients (Wong et al, 2009).