PSD4 and ductal breast carcinoma in situ: The same comparative analysis of PSD4 expression between DCIS and IDC, and then between primary tumors and paired metastases showed similar results to the Triple-Negative (TNBC) subtype (Supplementary Fig. 7b–d): higher expression of PSD4 in DCIS than in IDC, and higher expression in primary tumors than in metastases.