CHRNA7 and cancer: In addition to a7-nAChR, the homopentameric form of α9-nAChR has been reported to play important roles in promoting cancer cell proliferation (Lee et al., 2010), angiogenesis (Cooke, 2007), cancer metastasis (Wei et al., 2009), and apoptosis suppression (Paliwal et al., 2010) during carcinogenesis in response to tumor microenvironments.