Substance P is a neurokinin neurotransmitter, which is characterized by the C-terminal sequence, Phe-X-Gly-Leu-Met-NH2. Substance P is known to be an important part of endocrine and exocrine gland secretion. In addition, Substance P is essential in smooth muscle contraction, pain, inflammatory response including vasodilation, plasma extravasation and mobilization of immune system cells. Alternate studies suggest that Substance P is a key factor in cancer cell proliferation and that inhibition of this component can induce apoptosis in cancer cells and decrease the steady state of Her2 (Neu) and EGFR. Substance P inhibits the phosphorylation of ERK, which results in a reduction of capsaicin-induced nociception. Substance P is an activator of NK-1R.
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