Phosphorylation of NTAL in response to SCF. (A) HuMCs were challenged with SCF (100 ng/mL) for the indicated periods of time, and then the proteins were extracted and immunoprecipitated with either an anti-NTAL pAb or an anti-LAT mAb as described in “Materials and methods.” The lysates were then probed with an antiphosphotyrosine antibody (pY) or an anti-NTAL mAb or anti-LAT pAb. (B) Recognition of phosphorylated NTAL by anti-pY¹⁹¹ LAT antibody. Mouse BMMCs were sensitized and then stimulated with antigen for 120 seconds as described in “Materials and methods.” Cell lysates and NTAL immunoprecipitates, captured with anti-NTAL mAb, were prepared as in Figure 3 and then probed with antiphosphotyrosine mAb (pY) or anti–pY¹⁹¹-LAT (pLAT/NTAL) as indicated in the figure. C indicates control; T, treated. (C) HuMCs were challenged for the indicated periods of time, and then the cell extracts were probed using the anti–pY¹⁹¹-LAT antibody, other phosphospecific antibodies as indicated in the figure, or Syk to determine loading. (D) Sensitized cells were challenged with either NP-BSA (100 ng/mL), SCF (100 ng/mL), or a combination for the indicated periods of time. The extracted proteins were then probed for the indicated proteins. The blots are representative of up to 4 similar experiments.