The HLHm5 upstream sequences are replaced by those of E(spl)m8-HLH.
In a wild-type background no phenotype is seen.
E(spl)m8-HLH::E(spl)m5-HLHE(spl).PN is an enhancer of eye phenotype of Nspl-1
Addition of E(spl)::HLHm5E(spl).PN to Nspl-1 flies enhances the "split" eye phenotype.