(a) Constitutively active (CA) variants of Akt, IKKβ or MKK4 were retrovirally transduced into B cells cultured on 40LB-lo feeder cells (iGB-lo cells) on day 2 of the culture. The expression of CD80 on the gated IgG1+ CD138− infection-marker-positive iGB-lo cells was then analyzed by FCM on day 5. Here, MAP2K4 is linked to infection.