Fig. 4. Characteristics of MCF-7 cells after induction of differentiation. (A) To establish mammospheres, cells were seeded into 6-well plates in cancer stem cell culture media for 28 days, and phase-contrast microscopy was used to monitor mammosphere growth. Cell morphology was visualized using inverted microscopy (×100). Scale bar, 200 μm. (B) CD44+/CD24−/low populations were evaluated in MCF-7 cells and MCF-7 cell-derived breast cancer stem (BCS)-like cells. The square indicates the distribution of the CD44+/CD24−/low cell subpopulation. (C and D) Aldehyde dehydrogenase (ALDH) expression in human BCS-like cells, analyzed by flow cytometry. Diethylaminobenzaldehyde (DEAB) was used as the specific ALDH inhibitor in the negative control groups. The gating was based on binding to a control antibody. Results are expressed as mean±SD. Statistical differences were analyzed with Student’s t-test (**P<0.01 and ***P<0.001 vs. control). SSC-H, side scatter-height.