Of all the tested markers, CD24, SSEA-4, SSEA-1 (CD15) CXCR4, E-cadherin and CD44v6 were expressed on the EpCAM positive population of the tumorigenic luminal-like xenograft cells, and thus candidates for defining functionally different luminal tumor cell subpopulations (Table 2). Here, CXCR4 is linked to neoplasm.