Fig. 1. TrkB and TrkC signaling are essential for the survival of cultured murine embryonic cortical precursor cells. (A) Fluorescence micrographs of cortical precursor cultures co-transfected with plasmids encoding EGFP and the empty vector (control), dnTrkB, dnTrkC or both (dnTrkB/C), and then analyzed at 2 days for EGFP (green, GFP), and cleaved caspase 3 (red, casp 3). Cells were counterstained with Hoechst 33258 (blue) to show all nuclei. Arrows denote double-labeled cells. (B,C) Quantification of the percentage of EGFP-positive cells (B) with condensed, fragmented nuclei, and (C) positive for cleaved caspase 3 in experiments similar to A. In each panel, two experiments of four are shown. Error bars denote the s.e.m. Scale bar: 100 µm. ^*P<0.05, ^**P<0.01, ^***P<0.001 relative to control-transfected cultures.