Biology · Developmental Biology

The continued expression of engrailed and wingless is maintained by interactions between the Engrailed- and Wingless-expressing cells in Drosophila. The following statements are given regarding the cascade of events that occur for this interaction: A. The engrailed gene is expressed in cells where neither even-skipped nor fushi tarazu gene is active. B. The wingless gene is expressed in those cells that contain high concentrations of either Even-skipped or Fushi tarazu. C. Wingless is a secreted protein, diffuses to the surrounding cells, binds with the Frizzled and Lrp6 receptor proteins, and activates engrailed gene expression via Armadillo. D. Hedgehog protein activates the transcription of engrailed and also activates its own transcription. E. Hedgehog protein diffuses from cells and binds to the Patched receptor on neighbouring cells, enabling the transcription of the wingless gene. Which combination of the above statements correctly represents the maintenance of engrailed and wingless expression?