Enhancement of PI3K-PDK1 signaling partially restores in vitro differentiation potential of BCAP^−/−CD19^−/− B cells. Bone marrow B cells from BCAP^−/−CD19^−/− mice were infected with retrovirus vectors carrying cDNA encoding p65-PI3K (A) or PDK1 (A280V) (B). As a control, a retrovirus vector without cDNA was also infected (mock). Cells were cultured and assayed as in Figure 3A. The percentage of IgM⁺IgD⁺ cells is indicated in each panel.