Expression of Dref^CR1.Scer\UAS under the control of Scer\GAL4^hs.PB using heat shock causes lethality throughout developmental stages; less than half of the animals survive until the pupal or adult stage after heat shock at any stage. The surviving animals reach adulthood, but with a 2 day delay in development. Expression of Dref^CR1.Scer\UAS under the control of Scer\GAL4^hs.PB results in the formation of melanotic tumours. Expression of Dref^CR1.Scer\UAS under the control of Scer\GAL4^l(1)BP-1 results in some reduction in size of the salivary glands. BrdU incorporation is reduced in the salivary gland cells compared to control salivary gland cells. DNA replication in the imaginal ring cells is normal. Expression of Dref^CR1.Scer\UAS under the control of Scer\GAL4^l(1)BP-1 results in a significant reduction in BrdU incorporation in the S phase zone corresponding to the second mitotic wave in eye discs. Cells ectopically labelled with BrdU are seen in the very posterior region of the eye disc.

When expression is driven by Scer\GAL4^GMR.PS the eyes are roughened. Ommatidia and interommatidial bristles are irregular. Two copies of Dref^CR1.Scer\UAS cause ommatidia to fuse. Examination of BrdU incorporation indicates the S phase zone for the second mitotic wave posterior to the morphogenetic furrow is reduced.