First, the bi-functional binding of the BsAbs (anti-mPEG/anti-HER2 and anti-mPEG/anti-DNS) for HER2-positive (MCF-7/HER2 and SKBR-3) and HER2-negative (MCF-7) cancer cells were examined and Trastuzumab was used as a positive control. This evidence concerns the gene ERBB2 and cancer.