Tyrosine phosphorylation of CRKL and coimmunoprecipitation of BCR-ABL and CRKL. Lysates of cells expressing the indicated constructs were (A) immunoprecipitated with CRKL antisera and immunoblotted with 4G10, a monoclonal antiphosphotyrosine antibody; (B) immunoprecipitated with CRKL antisera and immunoblotted with CRKL antisera; (C) immunoprecipitated with CRKL antisera and immunoblotted with an ABL MoAb. KD refers to a tyrosine kinase defective mutant of BCR-ABL. Molecular weight markers are indicated on the left side of the panel.