GMR regulatory sequences drive expression of a mir-6-1 microRNA in which 22bp of sequences complementary to ec have been substituted into the precursor stem backbone at the position normally occupied by the mature mir-6-1 miRNA. This results in an artificial miRNA that targets 21bp within the ec gene. The targeted sequence is common to all ec transcripts (residues 4252-4273 of isoform SF1).
Flies carrying ecmiRNA.CG2904.GMR have a rough eye phenotype and extra interommatidial cells are present in the pupal retina.