Figure 3. A CD22-dependent tolerogenic program inhibits basal signaling in the Akt survival pathway and drives nuclear import of FoxO1.

(A) Western blot analysis of BCR signaling components in WT and Cd22-KO IgM^HEL B cells 30 minutes after stimulation of cells with the indicated liposomes or PBS as a control. STALs inhibit phosphorylation of signaling components of all major BCR signaling pathways and induce hypophosphorylation of Akt and FoxO1 in WT B cells, but not Cd22-deficient IgM^HEL B cells. Data are a subset of Supplemental Figure 4. (B) Analysis of FoxO1 staining in IgM^HEL B cells by confocal microscopy. Cells were stimulated for 2 hours with the indicated liposomes and stained with anti-FoxO1, phalloidin, and DAPI. Inserts are a representative cell at 3 times the magnification. Original magnification, ×63.