A protein kinase inhibitor specific for the Raf and MEK mitogen-activated protein kinases (MAPKs) with potential anti-neoplastic activity. Raf/MEK dual kinase Inhibitor RO5126766 specifically inhibits the kinase activities of Raf and MEK, resulting in the inhibition of of target gene transcription that promotes malignant transformation of cells. Both Raf and MEK are serine/threonine-specific kinases that respond to extracellular stimuli, such as mitogens, and are involved in the regulation of cellular processes, such as gene expression, mitosis, differentiation, and apoptosis.