Fig. 2.
BCR cross-linking induces tyrosine-phosphorylations of Btk and WASP. Serum-starved 1 × 108 RAMOS cells were stimulated with 100 μg/mL F(ab′)2 fragment of goat antihuman IgM antibody for the indicated times (0, 0.5, 3, 15, 30, and 60 minutes). Cells were lysed with Triton X-100 lysis buffer and, after preclearance, lysates were immunoprecipitated with the anti-WASP antibody 503 (A) or the anti-Btk antibody 48-2H (B). Immunoprecipitates were fractionated by SDS-PAGE and immunoblotted with the antiphosphotyrosine (APT) antibody 4G10 (A and B; top). These membranes were reprobed with the anti-WASP antibody 503 (A; bottom) or the anti-Btk antibody 43-3B (B; bottom).