Recent studies showed exogenous VIP feeds back to induce EGFR (epidermal growth factor receptor) and HER2 (human epidermal growth factor receptor 2) phosphorylation in breast cancer cells and inhibits the apoptotic effects of the RAS/RAF inhibitor sorafenib on cancer stem cells, suggesting there remain unknown downstream mechanisms of VIP [22,23,24,25]. Here, EGFR is linked to breast cancer.