FIGURE 4.

CEACAM1 engagement impairs activation of ZAP-70-related signaling elements. TALL cells were stimulated or not (unstim) with anti-CD3 (—), anti-CD3 plus 5F4 (5F4), or anti-CD3 plus mIgG1 (mIgG1) as indicated. The lysates were analyzed by IB with the indicated anti-p-Tyr. The p-SLP-76 was detected by IP with SLP-76 Ab followed by IB with anti-p-Tyr. Protein loading was verified by re-blotting the membranes with anti-LAT, SLP-76, PLCγ₁, ERK, and β-actin Abs, respectively. Only β-actin IB is shown. The results were representative of three independent experiments. Similar results were obtained with clonally expanded IEL and PBT cells.