CD68 and ductal breast carcinoma in situ: We examined human breast tissue samples of normal breast ducts (MCF10A-like), preneoplastic hyperplasia (MCFNeoT-like), ductal carcinoma in situ (DCIS, MCFT1-like) and invasive ductal carcinoma (MCFCA1-like), for evidence of a macrophage infiltration threshold, which we detected by the intensity of staining for the macrophage marker CD68.