Fig. 4. FFS activates low signaling and is regulated by Wg. All tissue is from MS1096 hemizygotes. (A-E) Heterozygous UasFFS^high, (F) heterozygous EP941 that drives endogenous ptc, (G) EP941/UasFFS^high, (H-J) UasWg/UasFFS^highh. FFS generated mild overgrowth of the anteroposterior axis of the wing and expansion of the costa, with no disturbance of wing hair polarity (A). It also expanded expression of Iro and dpp at the anterior margin of the wing pouch (arrowheads in B,C), and dpp in a line corresponding to the presumptive wing margin. ptc (D) and col (E) expression remained essentially normal, though there was a small gap in ptc expression at the presumptive wing margin. ptc overexpression reduced the size of the AP axis, abolished the L3/4 territory and much of L3 (F). ptc overexpression had no effect on the anterior overgrowth driven by FFS, though it transformed the L3/4 intervein to excess venation (G). UasWg in combination with UasFFS caused massive activation of Hh targets including dpp (H), ptc (I) and col (J).