Epithelial tumor lines typically express NKG2D ligands but are either negative for their NKG2D–DAP10 receptor or, as with the MCF-7, BT-20, and MDA-MB-453 breast cancer lines, scarcely positive as reflected by minimal shifts of flow cytometry profiles and very low NKG2D and DAP10 mRNA and protein expression (Figure S1A and S1B; also refer to Figure 2B and Figure 2C in references 3 and 9, respectively). Here, HCST is linked to breast cancer.