In addition, two important findings must be highlighted in cancer cells: the expression of the NK-1R is crucial for the viability of tumor cells (after its blockade, tumor cells die by apoptosis) and SP increases the expression of the NK-1R but not that of other tachykinin receptors (e.g., NK-2R) [14,15,17,72]. This evidence concerns the gene TACR2 and neoplasm.