Further functional studies have demonstrated an impact of Sdc-1 on breast cancer cell motility that could be linked to the regulation of E-cadherin, Rho GTPases, and focal adhesion kinase [17], a differential regulatory impact of membrane-bound and soluble forms of Sdc-1 on breast cancer cell invasion that affected the expression of protease inhibitors [18], and a novel immunomodulatory role of tumor Sdc-1, inducing CD4+ T-cell polarization in the breast cancer microenvironment [19]. This evidence concerns the gene CD4 and breast cancer.