TACR1 and cancer: Currently, there are many data demonstrating the involvement of the substance P (SP)/neurokinin-1 receptor (NK-1R) system in cancer [2,3]; one of these targets could be the NK-1R, and thus, a new antitumor strategy could be the use of NK-1R antagonists (e.g., the drug aprepitant), since it is known that SP (after binding to the NK-1R) promotes mitogenesis in tumor cells and that NK-1R antagonists (after binding to the same receptor) counteract the SP-mediated mitogenesis and induce apoptotic mechanisms in these cells [2,3].