While early DCIS lesions are well-contained within the basement membrane of the mammary ducts, later stages of DCIS are characterized by a dismantled basement membrane and the presence of micro-invasion, allowing cancer cells to invade outside into the stroma, a characteristic seen in Cav-1 KO mice treated with estrogen [1, 5, 28]. Here, CAV1 is linked to ductal breast carcinoma in situ.