Wnt/beta-catenin signaling, pivotal for pituitary development and hormone production, was also hyperactivated in a novel murine model of human AC: this tumor shares a number of traits (e.g., cyst formation, cell clusters with beta-catenin cytoplasmic accumulation, and Axin2-Lef1-Bmp4 expression) with its human counterpart, remarking once again the hypothesized role of this intracellular mediator in AC pathogenesis [38]. This evidence concerns the gene BMP4 and cyst.