Activation of Akt-ER alone is not sufficient to overcome inhibition of BCR-induced IL-2 production by BCR+FcγRIIB1 co–cross-linking.

Parental A20 cells or those transfected with the Myr Akt-ER or non-Myr Akt-ER were left unstimulated or stimulated for 24 hours by cross-linking the BCR alone (B), or by co–cross-linking the BCR with the FcγRIIB1 (B+F), in the absence or presence of 4-HT. Each stimulation condition was performed in triplicate. The supernatants were harvested after 24 hours and the presence of IL-2 was determined by a bioassay using the proliferation of the IL-2–dependent cell line CTLL-2 (see “Materials and methods”). The background CTLL proliferation in the absence of B-cell supernatants has been subtracted from all samples; the proliferation with 2 U/mL of recombinant human IL-2 is shown for reference.