Requirement for Akt1/2 for B1 B-cell development. (A) Representative analysis of peritoneal cavity lymphocytes from chimeras established with Akt1^+/+Akt2^+/− (top) or Akt1^−/−Akt2^−/− (bottom) progenitors 12 to 14 weeks previously. The leftmost plots are gated on viable donor-derived B cells (DAPI⁻ Ly5^B6+ CD19⁺). Numbers in plots show the frequency of events as a function of the indicated parent gate. (B) Average frequencies for the indicated subsets were calculated using the gates shown in panel A. B2, CD19⁺ B220⁺ CD43⁻; B1, CD19⁺ B220⁺ CD43⁺; B1a, CD19⁺ B220⁺ CD43⁺ CD5⁺; B1b, CD19⁺ B220⁺ CD43⁺ CD5⁻. Error bars indicate the SEM for each group; n = 5. Data are representative of 2 separate experiments. **P ≤ .01; ***P ≤ .005.