Akt1/2-deficient B cells exhibit a defective BCR-mediated proliferative response. (A) CFSE-labeled CD23⁺ follicular B cells were left unstimulated (top plots) or stimulated with 50 mg/mL anti-IgM antibodies (middle) or 1 μg/mL LPS (bottom) for 3 days, stained with the viability dye 7AAD, and analyzed by flow cytometry. The right-most overlay histograms were gated on viable (7AAD⁻) cells using the gates indicated in the corresponding plots. Black line indicates Akt1^−/−Akt2^−/−; gray filled curves, Akt1^+/+Akt2^+/−. (B) Mean numbers of viable Akt1^−/−Akt2^−/− or Akt1^+/+Akt2^+/− B cells recovered from triplicate cultures stimulated with the indicated concentrations of anti-IgM antibodies or LPS were calculated by flow cytometry using the 7AAD⁻ gates shown in panel A. Error bars indicate SEMs from 4 animals per group. Data are representative of 2 separate experiments. ***P ≤ .005.