CD38-mediated ZAP70 and MAPK activation depends on CD16 expression.

YT CD16⁺ and YT mock cells were prepared and incubated as described in the legend for Figure 3. ZAP70 activation was determined by immunoprecipitating the lysates with an affinity-purified rabbit polyclonal anti-ZAP70 antibody and by immunoblotting with the anti-pTyr RC20-HRP mAb (A, upper panel) and then by reprobing with rabbit anti-ZAP70 (Zap-4) serum (A, lower panel). ERK activation was determined by immunoblotting with an anti–diphospho-ERK mAb (B, upper panel). The filter was then stripped and reprobed with an antitotal ERK-2 antibody (B, lower panel). Data are from 3 independent experiments.