Figure 6.

Protein–tyrosine phosphorylation in Blk(Y495F)-induced lymphoid tumors. (A) Lymph nodes (lanes 1, 3, 4, and 6), spleens (lanes 2, 5, and 7), or thymuses (lanes 8–10) from Blk(Y495F) transgenic mice (lanes 1–6; lanes 8 and 9) or nontransgenic littermates (lanes 7 and 10) were dispersed and lysed. Phosphotyrosine-containing proteins in 10⁶ cell equivalents were detected by immunoblotting. The following transgenic mice were examined: Blk(Y495F)-15.4 (lanes 1 and 2); Blk(Y495F)-15.15 (lane 3); Blk(Y495F)-15.3 (lanes 4 and 5); Blk(Y495F)-29F (lane 6); Blk(Y495F)-16F (lane 8); and Blk(Y495F)-13.11 (lane 9). (B and C) B lymphoid tumor-bearing lymph nodes (B, lanes 1 and 3) and T lymphoid tumor-bearing thymuses (C, lanes 1, 3, and 5) from Blk(Y495F) transgenic mice were dispersed; splenocytes (B, lanes 2 and 4) and thymocytes (C, lanes 2, 4, and 6) from nontransgenic littermates were prepared in parallel. PLC-γ, PI-3K, and ZAP-70 were immunoprecipitated from 5 × 10⁷ cell equivalents of cell lysate, and phosphotyrosine was detected by immunoblotting as in A. The apparent sizes (in kDa) and positions of molecular mass standards are indicated at left. Arrowheads indicate individual proteins as described in the text.