Aggregation of FcϵRI induces the translocation of Cbl-b into the lipid raft. The cell homogenates of either nonstimulated or antigen (Ag)–stimulated RBL-2H3 cells were fractionated by sucrose density gradient centrifugation. The proteins were concentrated with 0.02% deoxycholic acid and 10% trichloroacetic acid, separated by SDS-PAGE, and analyzed by immunoblotting with anti-Cbl-b (upper), anti-Lyn (middle), and anti-FcϵRIβ antibodies (bottom). Molecular size markers are indicated at the left in kilodaltons. The results were representative of 3 experiments.