Inhibition of tumor growth, angiogenesis, and tumor cell proliferation by a small molecule inhibitor of c-Jun N-terminal kinase.

c-Jun N-terminal kinase (JNK) is a member of the mitogen-activated protein kinase family, and its function is critical for signal transduction in tumor and endothelial cells. JNK is a serine/threonine protein kinase that phosphorylates c-Jun, a component of the activator protein-1 transcription factor complex. We hypothesize that inhibiting JNK will lead to the inhibition of tumor growth; therefore, we evaluated the efficacy of the recently described JNK inhibitor SP600125 [anthra[1,9-cd] pyrazol-6 (2H)-one].