CSC are abundant in primary CD44
/CD49+ cancer cells. A) Representative dot plots for Ep-CAM/CD49f profile of tumor cells from different breast cancer patients as analyzed by flow cytometry (top) and histogram showing percentage of each Ep-CAM/CD49f population (n = 9 for normal breast and n = 13 for breast cancer samples). Lineage negative (CD45neg, CD10neg, CD31neg) cancer cells were gated followed by exclusion (gating out) of Ep-CAMneg/CD49fneg mesenchymal fraction. Numbers in the corners indicate percentage of cells in each quadrant. B) Expression level of each of the studied stem/progenitor cell markers in Ep-CAMhigh/CD49fneg and Ep-CAMhigh/CD49f + cell fractions in 16 breast cancer patients gated as in A. C) Percentage of CD44high/CD24low/Ep-CAMhigh cancer cells (top) and after fractionation into CD49fneg or CD49f + cells (bottom). Cases were stratified to four subtypes of breast cancers based on their estrogen receptor (ER), progesterone receptor (PR) status, as well as overexpression of Her2 as following: ER = ER+/PR+/Her2neg, ER/Her2 = ER+/PR+/Her2+, Her2 = ERneg/PRneg/Her2+, and basal = ERneg/PRneg/Her2neg, D&E) Mammosphere formation, measured by either number (D) or size (E) of tumor cells sorted for the stem/progenitor markers CD44high/CD24low or ALDHhigh and expressed within Ep-CAMhigh/CD49fneg or Ep-CAMhigh/CD49f + breast cancer cell subpopulations (means ± S.E.M, n = 7). **indicates statistical significance.