GMR regulatory sequences drive expression of the sbb B isoform, tagged at the 5' end with 8 tandem copies of Tag:MYC.
wild-type
R7 and R8 photoreceptor cell axons extend normally through the lamina to terminate in the medulla in animals expressing sbbB.GMR.T:Hsap\MYC.
sbbB.GMR.Tag:MYC rescues sbb2