Fig. 2

Expression of sialyl-glycolipid stage-specific embryonic antigen 4 (SSEA4) during chemotherapeutic treatment of breast cancer cells in vitro. Human breast cancer xenograft (HBCx)-17 cells containing different amounts of SSEA4-positive cells were treated with chemotherapeutic drugs in vitro (a). The half-maximal inhibitory concentration (IC₅₀) values (n = 3) for the commonly used drugs cisplatin (b), mafosfamide (c), 5-fluorouracil (d), and doxorubicin (Adriamycin/ADRIBLASTINA® RD) (e) were measured. The suspension cells showed higher IC₅₀ values, indicating an increased resistance to those drugs (f). To directly examine the phenotype of cells surviving the treatments, a purely adherent cell line derived from model HBCx-17 was treated with increasing concentrations of mafosfamide (g), 4-hydroxycyclophosphamide (h), or doxorubicin (i) (n = 4). **p < 0.01, ***p < 0.001. ADH adherent culture, SUS suspension culture