regulates invasion in SCC-25. (A) siRNA targeted knockdown of S1P1 was specific to S1P1 mRNA (qPCR, left), did not affect S1P2 or S1P3 mRNA (qPCR, middle panels). S1P1 down-regulation significantly reduced invasion (images of invaded cells, P < 0.001, far right). (B) Treatment with W123, an S1P1 inhibitor (1 μM), significantly reduced invasion (invasion assay, P < 0.05). (C) S1P1 knockdown significantly reduced IL-6 levels in conditioned media under S1P stimulation (P < 0.05, ELISA). (D) S1P1 knockdown reduced IL-6- and EGF-induced increases in p-STAT3 (Immunoblot). (E) Treatment with W123 (500 nM, 1 μM) reduced ERK phosphorylation in a dose dependent manner under S1P stimulation (Immunoblot). S1P was dissolved in ethanol. Means ± SE are presented, *p < 0.05, ***p < 0.001, ***p < 0.001.