Ma et al. (2014) have shown that the CD44+/CD24− cell population with cancer stem cell-like properties may play an important role in the aggressive behavior of TNBC. We also confirmed the increase in the stem-ness property of MDA-MB-231 cells, as more than 70% of the population of cells contain the cancer stem cell marker compared to the other TNBC (40%) and ER/PR+ve BC (6%) cell types. This evidence concerns the gene ESR1 and cancer.