In a study with ductal breast carcinoma in situ, D’Arcy and coworkers depleted SDC1 in MCF10A cells and observed an upregulation of EMT marker gene expression, including E-cadherin (CDH1), fibronectin-1 (FN1), and claudin-1 (CLDN1). Here, CLDN1 is linked to ductal breast carcinoma in situ.