The effect of LLnL on surface biotinylation of βc. (A) Ba/F₃ cells were depleted of IL-3 for 12 hours then stimulated with IL-3 (0.5 to 15 ng/mL) for 0 to 2 hours as indicated. βc immune complexes (10⁷ cells) were separated by SDS-PAGE (7% gel), transferred, and immunoblotted with RC20 antibody. (B) IL-3–depleted Ba/F₃ cells were treated with LLnL or carrier for 1 hour and stimulated with IL-3 for 0 to 2 hours before cell-surface biotinylation was performed. βc immune complexes (5 × 10⁷ cells) were separated by SDS-PAGE (7% gel), transferred, and immunoblotted with RC20 antibody. After stripping, the membrane was reblotted with streptavidin:HRP. The position of phospho-βc and biotinylated-βc is indicated.