Thus, while trastuzumab might also augment chemotherapy-induced tumor toxicity, causing attenuation of DNA repair activity and increasing apoptosis [27], our results strongly suggest that the reported synergy between trastuzumab and docetaxel in HER2-positive breast cancer patients and in nude mice bearing HER2-expressing tumors and treated with the two drugs in combination [27;28] depends on the increased ADCC rather than on the inhibition of HER2-mediated DNA repair by the antibody. Here, ERBB2 is linked to breast cancer.