This invention describes a protein nanoparticle system for targeting siRNA or other drugs into tumors. The basis of the protein system is elastin-like peptides that self-assemble once exposed to the nucleic acid of the siRNA. Specific targeting peptides are fused to the core ELP structure by standard genetic engineering techniques. These targeting peptides confer specific binding of the nanoparticle to receptors on the surface of tumor cells and allow for uptake of the nanoparticle into the tumor cells.
