MED12 and Fibroadenoma: Importantly, in addition to being mutated in >70% of UFs4, MED12 exon two mutations are also observed in breast fibroadenomas and phyllodes tumors (59%)60,61, uterine leiomyosarcomas (7–30%)62, chronic lymphocytic leukemias (5%)63, and colorectal cancers (0.5%)62.