In second instar eye-antenna discs, elB and noc reporter expression is restricted to the eye primordium. In early third instar discs, expression in the distal part of the antenna primordium is observed. In the eye-head primordium, elB and noc are expressed in the hth domain that indicates the proliferative region. In late third instar larval discs, expression levels remain high in the region anterior to the morphogenetic furrow, at more elevated levels in cells that co-express hth and tsh and at lower levels in the pre-proneural region. Thus elB and noc are expressed at higher levels in the proliferative region of the eye-head primordium.
The P{GAL4}elBGAL4 insertion site is reported to be 950 bp upstream of the elB transcription start site as defined by EST RE67722. The P insertion is in a positive orientation with repect to elB gene transcription.