PGR and ductal breast carcinoma in situ: Two DCIS cell lines, namely, MCF10DCIS.com (ER/ progesterone receptor/ HER2-negative) and SUM225 (HER2-positive) formed a basal and HER2-positive subtype xenograft model, respectively; both formed DCIS-like lesions during tumor formation and slowly developed to IDC.216 Valdez et al. identified the reproducible growth of patient-derived DCIS in NOD-SCID IL2rγ mice using the MIND model.217 In another study, the researchers found that only a proportion of the patient-derived DCIS (54%) line progressed to IDC over a median follow-up of nine months.218