In particular, electroacupuncture was found to mediate its analgesic effect in different animal pain models (cancer pain, muscle pain and inflammatory pain) through reducing spinal substance P concentration (SP) (Lee et al., 2009; Hsieh et al., 2014) and counteracting the upregulation of the neurokinin receptor 1 (NK1) (Zhang et al., 2005) as well as SP-NK1 downstream targets such as phosphatidylinositol 3-kinase and Akt (Kim et al., 2012). The gene discussed is TAC1; the disease is cancer.