Table 1.

Release of S1P from MCF-7 cells during coculture or staurosporine treatment

Sample	S1P (ng/ml)
MCF-7 cells
Control	n.d.
Staurosporine (0.5 ng/ml)	4.02 ± 1.51
siSphK2 + Staurosporine (0.5 ng/ml)	0.65 ± 0.12
Cocultures
Macrophages	n.d.
Macrophages + MCF-7	5.65 ± 2.79
Macrophages + MCF-7 siSphK2	n.d.
Macrophages + MCF-7-Bcl-2	n.d.

S1P contents in supernatants were measured with LC-MS/MS as described in Materials and Methods. Values are means ± SD; n ≥ 5. The lower limit of quantification was 0.5 ng/ml. S1P concentrations in supernatants below this limit are marked with n.d. MCF-7 cells were treated with staurosporine for 4 h, washed and suspended in full medium for 2 h followed by S1P determinations. Coculture conditions were as described in Materials and Methods.