Figure 7

Proposed model for the roles of Pros and dPax2 during cell fate decisions in the R7 equivalence group. Model depicting the outcome of Ras/MAPK and Notch (N/Delta (Dl signaling in the R7, anterior (a)/posterior (p) CCs, and equatorial (eq)/polar (pl) CCs based on the differences in Pros and dPax2 observed in these different cell populations. Phyllopod (Phyl) has been previously suggested to prevent dPax2 expression in the presumptive R7 [34]. In this model, the a/p CCs would be dominated by dPax2/Cut/Notch activity, whereas the eq/pl CCs would be dominated by Pros/pERK/Delta. Based on our LOF analysis, we propose that a/p and eq/pl CCs represent two distinct CCs that are inter-convertible. Moreover, in pros mutants, we postulate that four 'a/p' CCs form, whereas in dPax2 mutants, 'eq/pl' CCs form.