Increased kinase activity of JNK within cells transformed by p210 BCR-ABL (Bcr-Abl.A54) compared with IL-3–treated parental cells. (Top) Equal quantities (50 μg) of nuclear proteins isolated from the respective cells growing in medium (in the case of H7 parental cells including 5% WEHI CM as a source of IL-3) were placed in side-by-side solid-phase JNK activity assays. The reaction contents were then boiled and subjected to SDS-PAGE followed by autoradiography. JNK reactions were also performed at a range of cytosol protein concentrations with the same result. (Bottom) One hundred micrograms of each cell lysate was immunoprecipitated with anti-JNK antibody, then immunoblotted for JNK. The same result was obtained by direct immunoblotting.