PTTG1 and neoplasm: Importantly, PTTG has been identified as a key signature gene implicated in tumor metastasis (Tanase et al., 2009; Tong and Eigler, 2009; Liao et al., 2012), and its expression is significantly unregulated in various tumors including pituitary, thyroid, colon, ovary, testis, lung, and breast (Vlotides et al., 2007; Espina et al., 2009; Chen et al., 2011; Liu et al., 2015).