A 205bp fragment of the ftz 3' UTR has been inserted into the human α-globin 3'UTR sequence of the pLT vector (FBrf0053400) in which a ftz promoter (extending to +80bp) is fused in frame to lacZ, followed by a 3' fragment of the human α-globin gene which provides polyadenylation and transcript termination sequences, and also includes a sequence that directs transcripts to localize basally. The ftz 3'UTR fragment contains a sequence that directs transcripts to localize apically.