TACR1 and cancer: Many in vitro and in vivo studies have demonstrated that NK-1R antagonists (Aprepitant, L-732,138, L-733,060, CP-96,345, SR-140,333, NKP-608, RP-67,580) are broad-spectrum anticancer agents that act in a concentration-dependent manner [22,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104]; one of the primary mechanisms by which these antagonists induce an antitumor effect is by causing the death of many different cancer cell types by apoptosis (see Table 1 and Figure 2).