To improve the silencing efficacy of EGFR-1 and EGFR-2, siRNAs targeting EGFR-1 and EGFR-2 were electrostatically complexed with pH-sensitive carbonate apatite (CA) nanoparticles [142] and the anti-cancer effects of the complexes were assessed in a murine syngeneic breast cancer model. The gene discussed is EGFR; the disease is cancer.