Fig. (3) Inhibition of neurotrophin-induced beta-lactamase reporter activity in the cognate Trk receptor expressing cells. Cells were pretreated with indicated concentrations of K252a (▼), or AG879 (■) and GW441756 (▲) and then stimulated with NGF (TrkA cells, A), BDNF (TrkB cells, B), or NT-3 (TrkC cells, C), or Thapsgargin for all three cell lines for 5 hours before beta-lactamase assay was performed as described in Methods. Response Ratios were plotted for the indicated concentrations of each compounds (n=3 for each data point).