FOXO3 and central nervous system cancer: Notably, FOXO3a functions as a tumor suppressor in breast cancer (Hu et al., 2004; Zou et al., 2008) and natural killer cell neoplasms (Karube et al., 2011), and low FOXO3a expression is associated with poor prognosis in glioma (Shi et al., 2010), ovarian cancer (Fei et al., 2009), and nasopharyngeal carcinoma (Shou et al., 2012).