Expression of UAS fng in SerRX106 mutant wing discs during early third instar with ptcGal4 results in the ectopic expression of Gbe+Su(H)-lacZ (arrow in R, S). Note, that the expression of Gbe+Su(H)-lacZ is restricted to the ptc domain. (T) The ectopic expression of Gbe+Su(H)-lacZ is lost during later stages of development. (TIF) Analysis of the SerRX106HE31 double mutants.(A, A’) Figure S4 Pharate adults have halteres and wings with a proper margin, indicated by the innervated bristles characteristic for the margin (shown in higher magnification in (A’)). (B-I) Analysis of SerRX106HE31 double mutant wing imaginal discs. Expression of Gbe+Su(H)-lacZ (B), Wg (C) along the D/V boundary. (D) Expression of the two Notch targets in relation to that of Ap. The magnification of the region highlighted with the arrow in (D) accentuates the fact that expression of the Notch targets is restricted to Ap-expressing DBCs (E). (F) Expression of Gbe+- Su(H)-lacZ at the D/V boundary is extinguished in apUG035- SerRX106HE31 triple mutant wing imaginal discs. (G) Expression of Dl in SerRX106HE31 double mutant wing imaginal discs. (H, I) Expression of Gbe+Su(H) and Ap in a early third instar SerRX106HE31 double mutant wing imaginal disc. Expression of Gbe+Su(H)-lacZ is expands throughout the Ap-expressing dorsal half of the disc (arrows). (J-N) Expression of UAS fng in SerRX106HE31 double mutant wing imaginal discs results in the ectopic expression of Gbe+Su(H)-lacZ (J) and Wg (L) (arrow in J– M). The merge of (J–L) reveals that the ectopic expression of the marker is restricted to the ptc domain, even in late third instar. The expression of the markers in PBCs seen in wt and HE31 mutant discs (arrow in N) is missing. Note that the expression of Wg can be observed in a broad band throughout the ptc domain and is not restricted to the FB as in the wildtype. References 1. 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