Subsequently, in a preliminary study, Xekouki et al., showed evidence of an immunohistochemical expression of the YAP/TAZ in fetal and adult human pituitary cells as well as an increased expression in the poorly differentiated pituitary tumors (null cell adenomas, ACPs and PCPs), and all tumors with a large undifferentiated compartment [17]. This evidence concerns the gene YAP1 and pituitary tumor.