This pain is well sustained by the secretion of many nociceptive mediators like endothelin-1 (ET-1), proteases, nerve growth factor (NGF), protons, transient receptor potential vanilloid (TRPV), substance P, calcitonin gene-related peptide (CGRP), adenosine triphosphate (ATP), and bradykinin into the cancer microenvironment [6]. The gene discussed is NGF; the disease is cancer.