ERBB2 and breast cancer: Ligand-nanoparticle conjugate binds to the receptors (e.g., HER-2, EGFR, VEGFR, IGF-IR) expressed on the breast cancer, mediates internalization of nanoparticles through endocytosis, and releases the conjugated biomolecules by lysosomal degradation to the active sites of tumour cells [54].