Short pulses of IL-4 partially and transiently deplete active Cdc42 from the B-cell cytosol.

Detergent extracts of LPS-activated B cells were stimulated with IL-4 for 5 to 30 minutes. Cdc42-GTP was removed from extracts using GST-CRIB (from WASP) coupled to glutathione–Sepharose beads. Bound proteins were identified with Western blotting using anti-Cdc42 antibodies. Experimental groups were as follows: no addition of IL-4 (lane 1), addition of IL-4 for 30 (lane 2), 10 (lane 3), or 5 (lane 4) minutes. LPS extracts preloaded with GTPγS are shown in lane 5. All lanes were on the same membrane, but the exposure time was shorter for lane 5 because the signal was strong. Data are representative of 4 experiments.