Cutting Edge: Expression of the Transcription Factor E74-Like Factor 4 Is Regulated by the Mammalian Target of Rapamycin Pathway in CD8+ T Cells

T cell receptor activation inhibits expression of the E74-like factor (ELF) 4 and Kru ppel-like factor 4 genes to release naive CD8(+) T cells from their quiescent state. In this study, we show that ELF4 controls the ERKmediated proliferative response by maintaining normal levels of dual-specificity phosphatases 1 and 5 in CD8(+) T cells. In activated CD8(+) T cells, the mammalian target of rapamycin pathway inhibits ELF4 and Kru ppel-like factor 4 expression downstream of ERK and PI3K signaling. Our findings demonstrate that rapamycin could be used to modulate expression of this transcriptional network involved in cell-cycle regulation. The Journal of Immunology, 2010, 185: 3824-3828.