Formation of high molecular weight complexes by BCR-ABL mutants. (A) Expression in Cos-1 cells was controlled by Western blot analysis using an α-ABL antibody. (B) Cos-1 cell lysates were fractionated by size-exclusion HPLC. The fractions indicated on the bottom were analyzed by Western blot using an α-ABL antibody. Molecular weights (MWs) corresponding to HPLC fractions are given on the top. Expression of the endogenous ABL and the transgenes is indicated by arrows.