Deletion of the GMR86F11 cis-regulatory module from the first intron of the endogenous mid locus. In addition, a sfGFP tag has been introduced into the endogenous mid locus, at the C-terminal end of the open reading frame. A Disc\RFPDsRed.3xP3.cUa marker has also been inserted, downstream of the inserted sfGFP tag and upstream of the mid 3'UTR.