When an additional breast cancer cell line, MCF-7, was analyzed for its cancer stem cell pool, Syndecan-1 depleted cells revealed 0.31% (±0.3%) SP cells compared to 0.68% (±0.5%) in the control-siRNA transfected cells, corresponding to a Syndecan-1-dependent relative decrease by >40% (P<0.01, n=4) (Figure 1E). Here, SDC1 is linked to cancer.