Indeed, reports revealed that R-roscovitine, a potent inhibitor of cyclin-dependent kinase 2 (CDK2)/Cyclin E, inhibited ACTH expression in models of zebrafish (transgenic zebrafish with overexpression of the pituitary tumor transforming gene), mice (xenografted with AtT-20 cells), and primary cell cultures of surgically resected human corticotroph tumors [19,20]. This evidence concerns the gene CDK2 and pituitary tumor.