Because MCF7 cells are a well characterized, stable epithelioid breast cancer cell line expressing estrogen (Figure 1A), androgen, progesterone and glucocorticoid receptors [30], but not Ets1 (Figure 1B) [10], [41] and display increased clonogenicity upon Ets1 expression (Table 1), we selected them for further analysis. Here, ETS1 is linked to breast cancer.