Figure 1.

SPHK1 protein and S1P secretion are increased in breast cancer stem cells (CSCs) compared to adherent parental cells. (A) SPHK1 and phosphorylated SPHK1 protein expression was upregulated, while SPHK2 expression was downregulated in CSCs derived from MCF-7, SKBR3, HCC38, and MDA-MB-468 breast cancer cells. (B) S1P secretion was increased in CSC cultures compared to their respective parental cells. Bars represent the means ± s.d. of three independent experiments. Asterisks (*) indicate statistical significance compared with parental cells (p < 0.01, Student’s t-test).