For this purpose, the impact on the level of reactive oxygen species, the mitochondrial membrane potential, cell cycle distribution and the activity of caspases-3/7, -8 and -9 of PAMAM-doc-trastuzumab and PAMAM-ptx-trastuzumab conjugates was determined and compared with free docetaxel and paclitaxel toward HER-2-positive (SKBR-3) and negative (MCF-7) human breast cancer cell lines. The gene discussed is ERBB2; the disease is breast cancer.