NEUROD1 and prolactin-producing pituitary gland adenoma: In prolactinomas, the average numbers of cells expressing given markers were: prolactin 45.8±5.6% (from 40% to 55%); ACTH 0.05±0.08% (0-0.2%); GH 0.03±0.04% (0.04-0.1%); and NeuroD1 98.9±0.6% (98.2-99.3%).