FIGURE 6.

Imp signaling opposes T cell migration induced by sphingosine phosphate. A, Western blot, and B, reverse transcriptase-PCR analyses of Imp induction by sphingosine phosphate. CD62^hi-CD44^lo CD4 T cells were isolated from 6-week-old B10BR mice and cultured for 24 h in the presence of increasing concentrations of sphingosine phosphate, as indicated. PCR data are expressed as mean ± S.D. The analyses were performed exactly as described under “Experimental Procedures.” One representative of three experiments is shown. C, reverse transcriptase-PCR analysis of S1P1 (left) and S1P4 (right) in CD4 T cells transduced with empty vector or Ras^V12G37. The cells were sorted for GFP expression at 96 h after spin infection and immediately used for the analysis. The data are expressed as mean ± S.D. D, analysis of chemotactic response of CD4 T cells to SP. Following treatment of transgenic mice with a doxocycline diet for 2 weeks, Ras^V12G37-positive (dark) or wild type (light) CD4 T cells were isolated from mice and used in a Transwell migration assay exactly as described under “Experimental Procedures.” The data are expressed as mean ± S.D. One representative of 3 experiments is shown.