Fig. 4. EGFR/Ras signaling is sufficient to activate Iro-C expression. (A-D) Ectopic mirr-lacZ and Ara/Caup expression (red; arrows) associated with clones ectopically expressing either EGFR (A,B) or Ras^V12 (C,D). Clones are marked either by loss (A,B) or gain (C,D) of GFP expression. Cells co-expressing GFP and mirr-lacZ appear yellow. EGFR-expressing clones are associated with ectopic mirr-lacZ and Ara/Caup expression in some regions of the prospective wing hinge, but not others (A; see also Fig. 5); they can also induce mirr-lacZ expression in the prospective wing blade (B). Ras^V12-expressing clones activate mirr-lacZ (C) and Ara/Caup (D) expression in a more penetrant and strictly autonomous fashion within the wing hinge and blade (but not within the medial notum), as indicated by the exact correspondence between the clone marker (GFP, green) and mirr-lacZ or Ara/Caup (red) expression (overlapped expression appears in yellow). Note that Ara/Caup is normally expressed in localized patches of anterior compartment cells within the prospective wing blade; these appear red instead of yellow in D (left-hand panel).