On the other hand, β-arrestin deficiency increases the sensitivity of U-251 MG and U-87 MG glioma cells to treatment with NK-1R antagonists L-732,138 and [D-Arg1, DTrp5,7,9, Leu11] SP increases cell apoptosis and G2/M phase arrest [27]. This evidence concerns the gene TACR1 and central nervous system cancer.