The DLK1 expression levels yielded an H-score of 256.3±11.6 in somatotroph adenomas, 124.7±7.3 in lactotroph adenomas, 79±4.7 in gonadotroph adenomas, and 83.1±7.9 in corticotroph adenomas (P<0.001). This evidence concerns the gene DLK1 and ACTH-producing pituitary gland adenoma.