Sequence encoding mCherry has been inserted into the first coding exon of E(spl)m8-HLH, using the native ATG as the initiation codon for the mCherry sequence (this is expected to result in the expression of the mCherry protein under the control of endogenous E(spl)m8-HLH regulatory sequences. SV40 termination sequences are present immediately 3' to the mCherry sequence, and thus the insertion is expected to result in a loss of function allele of E(spl)m8-HLH. A single FRT site is present downstream of the SV40 termination sequence.