TACR1 and central nervous system cancer: Substance P (SP) and the NK-1R system are widely known to positively correlate with cancer progression (e.g., osteosarcoma, melanoma, retinoblastoma, hepatoblastoma, glioma, rhabdoid tumors, acute myeloid leukemia, and lung carcinoma) [5,6,7,8,9,10,11,12].