The plasmid pGEX-GST-AGR2 was transformed into the engineering strain BL-21 and the GST-tagged AGR2 protein was expressed. After purification with glutathione sepharose beads (GE healthcare) by affinity chromatography, the GST-AGR2 fused protein was linked to sepharose beads for positive selection. After being washed several times with W1 buffer (25 mM Tris-HCl pH 7.5, 150 mM NaCl, 0.07% b-mercaptoethanol, 1% Triton X-100), the final purified AGR2-GST-beads were stored in sterilized PBS buffer. Flow cytometry analysis with TAMRA-labeled anti-AGR2 monoclonal antibody (Santa Cruz) and SDS-PAGE indicated that the GST-AGR2 fused protein was successfully linked to the sepharose beads.