Figure 9.

Model of activation of gsc transcription via the DE and PE. DE-mediated gsc regulation is regulated by two phases. During the early inductive phase, XWBSCR11 acts through the DE to stimulate gsc transcription. FoxH1 binds to the PE and cooperates to activate transcription, perhaps via the bending of DNA bringing the DE and PE in close proximity, thereby forming a large transcription complex among these various factors. During the late maintenance phase, Mixer/Milk homeoproteins bind to the DE, and Xtwn and Xsia homeoproteins bind to the PE to affect gsc transcription. It is unclear at present how the interplay among these transcription factors modulates the activity of gsc.