The phenotypes observed in Pten-deficient NKT cells are PI3K dependent. (A, top) Decreased maturation. Thymic Vα14iNKT cells from mice of the indicated genotypes were analyzed by flow cytometry for percentages of stage 3 cells. (A, bottom) Increased expression of Ly49C/I receptors. The αGalCer-CD1d⁺TCRβ⁺NK1.1⁺ cells in the top panel were analyzed by flow cytometry to determine relative expression levels of Ly49C/I. (B) Impaired proliferation. The NK1.1⁺TCRβ⁺ cells from panel A were stimulated by incubation with αGalCer-loaded DCs, and [³H]-thymidine incorporation was measured. Data shown are the mean ± SEM for 3 mice per group. **P < .01. For both panels, the defects of Pten-deficient Vα14iNKT cells were partially rescued by mutation of a PI3K subunit (p110γ or p110δ).