Expression of ELC/MIP-3β-SEAP-His6 and SEAP-His6 fusion proteins. (A) ELC/MIP-3β-SEAP-His6 and SEAP-His6 were purified from the conditioned medium of transfected cells by metal affinity chromatography, fractionated on 10% polyacrylamide gels, and stained with Coomassie brilliant blue. Arrowheads indicate ELC/MIP-3β-SEAP-His6 (left) and SEAP-His6 (right). The positions of size markers are shown on the left. (B) Real-time analysis of the interaction between ELC/MIP-3β or SEAP-His6 and U12-, EBI1/CCR7-, or pCEP4-expressing K562 cells, as monitored by SPR (Biacore). The SPR signal was expressed as resonance units (RU). ELC/MIP-3β-SEAP-His6 was immobilized on an NTA sensor chip, and K562 cells stably expressing U12, EBI1/CCR7, or pCEP4 were injected. Association and dissociation starts are shown by the left and right arrows, respectively. Representative binding curves for the interaction of ELC/MIP-3β with K562 cells transfected with U12 or EBI1/CCR7 and with parental pCEP4 cells are shown. The tracings are from a single experiment that was representative of three separate experiments.