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. Author manuscript; available in PMC: 2015 May 29.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2014 May 23;3(4):281–300. doi: 10.1002/wdev.140

Figure 7.

Figure 7

Fkh (likely in collaboration with Sage and Sens) keeps the SG alive until the prepupal stage by preventing expression of the apoptosis inducers reaper (rpr) and head involution defective (hid). Fkh (and Sage +/- Sens) in combination with low level ecdysone signaling activate transcription of the Salivary glue secretion (Sgs) genes in late larvae. High-level ecdysone signaling just prior to pupation activates expression of the early ecdysone-responsive genes, which encode transcription factors. A subset of these transcription factors repress fkh and Sgs transcription and activate expression of genes required for glue secretion. Thus, the glue is secreted when Fkh begins to disappear. In turn, the disappearance of Fkh results in rpr and hid expression, which overcome DIAP and activate the cell death pathway. Thus, the SG dies shortly after it completes its final task of glue secretion.