The Retinoblastoma protein, pRB, has been suggested to be a key protein in the pituitary tumorigenesis because of the pituitary tumors developed by RB+/- mice [22], but no RB mutations, apart from few high aggressive pituitary carcinomas [23], have been so far reported in human pituitary pathology [24]. The gene discussed is RB1; the disease is pituitary adenocarcinoma.