The World Health Organization (WHO) Classification of Tumors of Endocrine Organs, in its fourth edition, bases the classification of pituitary tumors on specific transcription factors, namely, pituitary-specific positive transcription factor 1 (Pit-1), Tbox family member TPIT (Tpit), and steroidogenic factor 1 (SF-1), involved in the differentiation of anterior pituitary cells [1]. Here, POU1F1 is linked to pituitary tumor.