The release of SP from TC cells suggests both an autocrine action (Figure 1) of SP binding to NK-1R that is overexpressed in TC cells and induces TC cell proliferation, and a paracrine action (Figure 1) of the peptide on NK-1R-expressing endothelial cells, potentially inducing proliferation and promoting neovascularization within and around the tumor, thereby enhancing TC growth [15,45]. Here, TACR1 is linked to neoplasm.