Specific silencing of S1PR1 in Ly3 ABC-DLBCL tumor cells inhibited tumor growth and invasion in vivo. (A) Ly3 tumor growth was inhibited by specific S1PR1 silencing; N = 8. ***P < .001. Data are representative results from one of 2 independent experiments. (B) Inhibiting S1PR1 by shRNA in ABC-DLBCL tumor cells was accompanied by a reduction in lung invasion in vivo. Lung nodules were numerated on day 20; N = 8. *P < .05. (C) Knocking down S1PR1 reduced expression of STAT3 target genes in vivo. Western blot analysis to detect expression of STAT3 downstream genes at protein level, using whole tumor lysates prepared from tumors grown from control and S1PR1 shRNA expressing Ly3 ABC-DLBCL tumor cells. Eight tumors were pooled to prepare the lysates. (D) Real-time PCR to analyze RNA expression levels of Stat3 downstream genes involved in proliferation, survival, and immune response in tumors grown from control and S1PR1 shRNA-transduced tumor cells. Eight tumors were pooled to prepare RNA, and real-time PCR was performed as triplicates for each sample. ***P < .001; **P < .01.