A method is provided for the treatment of a condition mediated by raf kinase, which includes administering a guanylhydrazone to a subject in need thereof. A method is also provided, which includes modulating or inhibiting signal transduction in a c-raf pathway with at least one guanylhydrazone. Another method is provided, which includes contacting one or more human mononuclear cells with at least one guanylhydrazone and at least one lipopolysaccharide to obtain one or more treated cells; contacting at least one selected from the group including said treated cells, one or more lysates thereof, and combinations thereof, with at least one surface-bound peptide in a surface-bound peptide array; and selectively modulating or inhibiting the phosphorylation of the surface-bound peptide.