ERBB2 and breast cancer: However, cell uptake is not always achieved as noted for trastuzumab, an FDA-approved humanized monoclonal antibody against Her-2/neu tyrosine kinase receptor, that induces quite limited HER-2 receptor internalization in Her-2/neu positive metastatic breast cancer models [4,5,6,7,8,9], yielding good cell targeting but poor cell uptake.