To directly compare neurotrophin dependence of DRG neurons expressing EWS-Pea3 from the Tau locus at a precocious versus isochronic time of onset, we generated a strain of mice in which Cre recombinase is expressed from the PV locus (Figure S4). The expression of GFP in TaumGFP/+ PVCre/+ was restricted to PV+ proprioceptive DRG neurons and mirrored the onset of expression of PV at approximately E14 (Figure S4; data not shown). We next cultured E14.5 whole DRG explants from TauEWS-Pea3/+ PVCre/+ and TaumGFP/+ PVCre/+ mice for 48 h in vitro in the presence or absence of NT-3 (Figure 5). We found that DRG neurons from both genotypes survived and extended neurites only in the presence of NT-3, whereas they died in the absence of NT-3 (Figure 5). Together, these findings suggest that only precocious but not isochronic ETS signaling in DRG neurons is capable of uncoupling survival and neurite outgrowth from a requirement for neurotrophin signaling normally observed in wild-type DRG.