Fig. 3. Fluorescent TrkA-Ros fusion proteins are functional. (A) A fluorescent TrkA-Ros fusion protein signals in response to NGF. Stable NIH3T3 cell lines expressing TrkA-Ros-sgBFP were subjected to NGF stimulation as indicated and TrkA-Ros-sgBFP autophosphorylation and Erk1/2 activation were detected by immunoblotting with lysate aliquots (upper panels). TrkA-RossgBFP autophosphorylation was also measured with immunopreciptated receptor (lower panel). Experiments with the parental cells are shown for comparison. (B) A fluorescent TrkA-Ros fusion protein transduces biological signals. NIH3T3 cells, stably expressing TrkA-Ros-sgBFP, were stimulated with NGF as indicated, and focus formation (upper panel) or proliferation (lower panel) were assessed.