Indeed, in vitro and in vivo studies have shown cyclin E overexpression in corticotroph pituitary tumors, mainly associated with dysregulation in pituitary tumor transforming gene (PTTG) and in Brahma-related gene-1 (Brg1) genes, both involved in the regulation of corticotroph cells cycle (44–46). This evidence concerns the gene PTTG1 and pituitary tumor.