Beta-catenin, a protein weighing 92 kD, is generally situated within the cell’s cytoplasm, specifically near the membrane. Alterations within the beta-catenin gene lead to the buildup of this particular protein inside the nucleus. The buildup of this protein inside the nucleus has been observed in fibromatosis (desmoid tumors) affecting the breast and abdomen, thus aiding in distinguishing it from alternative spindle cell neoplasms that could manifest in these areas.