Fig. 2. Survival-promoting activity of E4BP4 over-expressed in motoneurons. (A) Effects on motoneuron survival following trophic deprivation. E14 rat motoneurons electroporated with a plasmid encoding GFP (control) or with GFP and E4BP4 were seeded in the absence or the presence (not shown) of the neurotrophic factor BDNF. Survival values were expressed as a percentage of the value in BDNF at the same stage (see text). E4BP4 provided nearly complete protection against cell death at 24 hours or 48 hours after seeding. In long-term cultures (5 days in vitro, 5 d), the survival promoting effect was barely significant. Values are means ± s.e.m.; n=3-5 independent experiments. Statistical significance was calculated by Student's t-test (two-tailed). (B) Protection by E4BP4 against cell death triggered by Fas death receptor. Motoneurons electroporated with control and E4BP4 plasmids were exposed to soluble Fas ligand (sFasL) in the presence of BDNF. Survival is expressed as a percentage of the value in controls without sFasL (mean±s.e.m., n=3). (C) Effects of the PI3K inhibitor LY294002 (LY) on motoneuron survival induced by E4BP4. Survival is expressed as a percentage of the value for control neurons in BDNF. Mean±s.e. m.; n=4.