Utilizing this noncovalent approach, HK polymers containing siRNA directed against Raf-1, which has an important role in tumor angiogenesis, was able to effectively reduce xenograft tumor size by approximately 50% following multiple systemic dosing of 50 μg of HK/Raf-1 siRNA complexes during tumor growth, with no overt toxicity detected [32]. The gene discussed is RAF1; the disease is neoplasm.