The third gene we analyzed was PTTG2 (pituitary tumor transforming 2), as its paralog PTTG1 encodes a tumorigenic protein implicated in promoting proliferation of pituitary tumor cells (Domínguez et al., 1998; Zhang et al., 1999; Vlotides et al., 2007). Here, PTTG1 is linked to pituitary tumor.