TAC1 and neoplasm: Infiltrating nerve fibers, in turn, release neurotransmitters (e.g., norepinephrine, acetylcholine) and neuropeptides (e.g., substance P, calcitonin gene-related peptide) that influence not only tumor growth, angiogenesis but also immune cell polarization, T cell exhaustion, dendritic cell maturation and myeloid derived suppressor cell recruitment.