Downregulation of S1P2 decreased CCL2 expression in NB cells. (A) SK-N-AS cells were transfected with S1P2 siRNA or NS siRNA, serum-starved and stimulated with S1P (1μM) in 1 ml SF media for 24 h followed by CCL2 ELISA. (B) SK-N-BE(2) cells were transfected with S1P2 siRNA or NS siRNA, serum-starved and stimulated with S1P (100nM) in 1 ml SF media for 4 h followed by quantitative real-time PCR to check the S1P2 knockdown efficiency (left) and CCL2 ELISA (right). *, P< 0.05, **, P< 0.01 versus non S1P-treated controls or NS siRNA (B, left). #, P < 0.05, ##, P < 0.01 as indicated.