TLR7 and cancer: SP or NK-1R boosts the survival of activated T cells, triggers macrophages to secrete pro-inflammatory cytokines, and facilitates neutrophil chemotactic and migratory capabilities induced by CCL5.113–115 However, in thyroid cancer, SP binding to NK-1R can promote cancer growth, prevent cell death, and increase cancer spread and blood vessel formation.116 SP can also promote tumor metastasis by activating Toll-like receptor 7 on breast cancer cells through the action of extracellular RNA.117