FIGURE 2:

Syk activity is required for enhanced phosphorylation of FcεRIγ ITAMs in RBL-Lyn^KO cells. (A, B) Representative immunoblots probed for (A) total FcεRIγ or (B) phosphorylation (pTyr) comparing RBL-WT, -Lyn^KO, and -Lyn/Syk^dKO cells before (No Tx) or after 8 min of 1 µg/ml DNP₂₅-BSA cross-linking. Blots are displayed with different contrasts (low, medium, high) to visualize lower levels of ITAM phosphorylation in the knockout cells. pY1, pY2, pY3, and pY4 indicate the band corresponding to the respective number of phosphotyrosines in the γ-dimer. (C) Quantification of the immunoblots described in B to determine the percentage that each pTyr FcεRIγ band contributes to total FcεRIγ phosphorylation. (mean ± SD); No Tx n = 3, +8′ DNP₂₅-BSA n = 5. **** P < 0.0001, *** P < 0.001, ** P < 0.01, * P < 0.05, analysis of variance (ANOVA) with Tukey’s multiple comparisons test.