A TI{T-GEM.0} Trojan-Gal4 expression module (T-GEM) has been inserted into the intron separating exons 10 and 11 of EHR. The insertion is in the correct orientation to gene trap EHR with the Trojan GAL4 exon: the splice acceptor ensures that the T2A-GAL4 open reading frame is incorporated into the EHR mRNA, while the T2A sequence is expected to truncate the native EHR gene product and promotes the separate translation of the GAL4 open reading frame. Thus GAL4 driver expression is driven by the native EHR regulatory sequences.