SDS-polyacrylamide gel analysis of purified IGF1R-CD. (A) IGF1R-CD was Ni-NTA column purified from T ni insect cells, and the purity of the fusion protein was examined in aliquots from different steps of the purification. Lane 1, whole infected cell lysate; Lane 2, supernatant sample; Lane 3, cell debris after lysis; Lane 4, wash step fraction; Lane 5, elution step fraction 1; Lane 6, elution step fraction 2; M, molecular weight marker. Proteins were separated by 15% SDS-PAGE, and stained with Coomassie blue dye. (B) Parallel samples were immunoprecipitated using a polyclonal antibody against His-Tag and then Western blotted with an anti-IGF1R antibody.