Fig. 4.

Characterization of CHO cell lines stably expressing fusions between EpCAM and MCSP domains. a Schematic depiction of fusion proteins between EpCAM and MCSP. All fusion proteins use the transmembrane and cytoplasmic domain of human MCSP; PM plasma membrane. b Structure of EpCAM/CD3-bispecific BiTE antibody MT110. The overall structure is similar to that of MCSP-specific BiTE antibodies (see Fig. 1a). For purification and detection MT110 also contains a hexahistidine tag. c Expression of EpCAM/MCSP fusion proteins on the surface of stably transfected CHO cell lines. Cells were stained for FACS analysis with the parental anti-EpCAM antibody of MT110 and a PE-conjugated monoclonal anti-mouse-IgG antibody. d Quantitation of EpCAM-specific binding sites on the surface of transfected CHO cell lines