FIGURE 5.

Down-regulation of phosphorylated CD79a and Btk in 70Z/3-KD cells. The serum-starved cells of 70Z/3, 70Z/3-KD, or 70Z/3-KD-re were treated with anti-pre-BCR antibody (SL156) at the indicted concentrations for 5 min and solubilized in lysis buffer as described under “Experimental Procedures.” Whole cell lysates were subjected to 10% SDS-PAGE. A, protein expression and phosphorylated forms of CD79a. The cell lysates were immunoprecipitated by anti-CD79a Ab, and the immunoprecipitates were resolved by SDS-PAGE on a 7.5% gel, transferred to a PVDF membrane, and probed with the PY20 (upper panel) and CD79a (lower panel). Increased phosphorylation of CD79a was maximal by 5 min. The quantitative data of phosphorylated CD79a were represented as the mean ± S.D. (n = 3). B, protein expression and phosphorylated forms of Btk are indicated in Western blot. The blots were probed with anti-p-Btk Ab (upper panel) or anti-Btk Ab (lower panel). The quantitative data of phosphorylated Btk are represented as mean ± S.D. (n = 3).