Cross-talk between human epidermal growth factor receptor 2 and 3 (HER2 and HER3) may potentially contribute to therapeutic resistance in human breast cancer. Subtractive phage display allows highly specific selection for antibody fragments directed against cells surface HER2 and HER3. The strategies to select conformation- and activation-specific antibodies against HER2 and HER3 require tightly regulated HER2 and HER3 expressing cells that allow controlled activation/inactivation of these receptors during panning procedures. To achieve this, first, we found that the VERO cell line is an appropriate cell line for heterogeneous expression of HER2 and HER3, and then we established a panel of VERO stable cell lines expressing high levels of HER2 and HER3 alone and in combination. We also showed that HER2 and HER3 expressed in VERO cells were biologically active and could form heterodimer following neuregulin1 treatment. The cell line established here not only provided platforms for phage display-based methods but also could be used in any HER-related studies.