Figure 13.

Combination effects of SPHK inhibitors and doxorubicin (Dox) against MDA-MB-468 parental and CSCs. Cells were treated with a sub-lethal concentration of SPHK inhibitors in combination with doxorubicin for 72 h. Cell viability was determined by the MTT or MTS assay. The dashed line represents the cell viability following treatment of the indicated concentrations of FTY720, PF543, ABC294640, and SK1-II. Points represent the mean ± s.d. of three independent experiments. Asterisks (*) indicate statistical significance compared with cells treated with either doxorubicin or SPHK inhibitors alone (p < 0.05, Student’s t-test).