Comparative analysis of human leukemia cell lines differing in expression of p210 BCR-ABL for JNK activity. (A) Equal quantities of cell lysate from HL-60 versus K562, a p210 BCR-ABL transformed cell line, were placed into solid-phase JNK activity assay or were immunoblotted for expression of c-jun. (B) Equal quantities of cell lysate from M07e cells growing in GM-CSF versus M07p210 cells were placed into solid-phase JNK activity assay or were immunoblotted for expression of c-jun, c-fos, ATF-2, or JNK. Note absence of difference in abundance of JNK (isoform 1) or ATF-2 between cells, but major increase in c-jun (2.8-fold by densitometry) and c-fos (2.4-fold) proteins in M07p210 that mirrors increase in kinase activity of JNK.