Western blot analysis to determine the specificity of the anti–SPAN-Xb antibodies.

(A) Coomassie blue staining of a 12% SDS-polyacrylamide gel showing the loading of SPAN-Xb recombinant protein and a control recombinant protein Sp17 (M indicates protein marker; lane a, SPAN-Xb; and lane b, Sp17). (B) Western blot analysis using diluted sera (1:1000) showing the presence of antibodies directed at SPAN-Xb and not Sp17 in patients with hematologic malignancies. Lane 1 indicates serum from patient with CML; lane 2, serum from patient with CLL; lane 3, serum from patient with AML; and lane 4, anti–6-His tag monoclonal antibodies. (Lane a, SPAN-Xb recombinant protein; lane b, Sp17 recombinant protein.)