MMEL1 and retinal degeneration: We made use of the rough eye/disorganised ommatidia phenotype, and found that co-expression of NEP2 using the EP(3)3549 Drosophila strain, with the GMR-GAL4 driver almost completely suppressed both the external disorganised ommatidia and internal retinal degeneration of the AβpE3-42 expressing flies (Fig. 3a).