Role of PI3K in regulating protein synthesis and cell size of activated T cells. (A-B) FACS histograms show expression of the amino acid transporter subunit CD98 and the transferrin receptor CD71 on the surfaces of antigen-primed P14 LCMV CD8⁺ T cells cultured in medium alone, 20 ng/mL IL-2 (CD8^IL-2), or 20 ng/mL IL-2 (CD8^IL-2) plus 10 μM LY294002, a PI3K inhibitor, for 24 hours. (C) FACS dot plots and histograms of FSC and SSC profiles of antigen-primed P14 LCMV CD8⁺ T cells maintained for 48 hours in medium, 20 ng/mL IL-2 (CD8^IL-2), or 20 ng/mL IL-2 (CD8^IL-2) plus 10 μM LY294002. (D) Incorporation of tritiated [³H]-amino acid (aa) into precipitated cellular protein of antigen-primed P14 LCMV CD8⁺T cells maintained for 48 hours in medium, 20 ng/mL IL-2, or 20 ng/mL IL-2 plus 10 μM LY294002, a PI3K inhibitor. (E) Percentage maximum values of tritiated [³H]-amino acid (aa) uptake by antigen-primed P14 LCMV CD8⁺ T cells maintained for 48 hours in medium or in the indicated concentration of IL-2 ± 10 μM LY294002. (F) Protein concentration of antigen-primed P14 LCMV CD8⁺ T cells maintained for 48 hours in medium, 20 ng/mL IL-2 (CD8^IL-2), or IL-2 plus 10 μM LY294002. (D,F) Error bars indicate SD. (G) Percentage maximum values of tritiated [³H]-amino acid (aa) taken up by antigen-primed P14 LCMV CD8⁺ T cells maintained for 48 hours in medium or in the indicated concentration of IL-15 ± 10 μM LY294002. Dot plots, histograms, and graphs are representative of the results of 5 or more experiments. (D-E, G) P = .001. (F) P = .05.