The construct was composed of a 5.8 kb fragment of the nestin promoter upstream of the sequence for optimized phiC31 recombinase (phiC31*), with the 1.8 kb second intron containing the neural stem/progenitor cell-specific enhancer downstream of the recombinase sequence. The SV40 polyadenylation sequence was also cloned into the vector. The linearized, purified construct was injected into pronuclei of fertilized one-cell embyros. Only one founder line was established. Mice show wide expression of phiC31 mRNA in the nervous system with no expression observed in non-neural tissues like somites. High expression is observed in the ventricular zone of the developing nervous system.