JNK activity assay on lysates of cell lines and a leukemic blast crisis bone marrow sample from a patient with a transformed myeloproliferative disorder containing a Philadelphia chromosome. Both the human cell line model of acute leukemia formed in the presence of a Philadelphia chromosome (K562) and the primary patient sample containing Philadelphia chromosome show strong constitutive JNK activity. Another Ph⁺ acute leukemia (not shown) also demonstrated a similar level of activity.