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. Author manuscript; available in PMC: 2016 Oct 26.
Published in final edited form as: Dev Cell. 2015 Oct 26;35(2):151–161. doi: 10.1016/j.devcel.2015.09.015

Figure 7. Ectopic EGF receptor signaling induces square cell packing and Pins asymmetry.

Figure 7

(A) Expanded EGFR signaling induces a broader region of square-like cells in argos mutants and in embryos that ubiquitously express secreted Spitz (sSpitz) or Pointed P1 (PntP1) with the da-Gal4 driver. (B) Increased percentage of four-sided cells in the lateral region (excluding cells in the two most ventral rows on both sides of the midline) of argos (p = 0.02), da>sSpitz (p = 0.02) and da>PntP1 (p = 0.03) embryos compared to wild type (unpaired t test, n = 193–397 cells in 3 embryos/genotype). (C) Using the en-Gal4 driver to produce ectopic expression in stripes outside of the Cnc domain, expression of sSpitz and Cnc together, but not either one alone, induced apicobasal cell elongation characteristic of the square cell grid. (D) Expression of sSpitz with the en-Gal4 driver induced Pins asymmetry in dividing cells adjacent to this domain (0/24 dividing cells in control en>mCherry:Moesin embryos compared to 39/45 dividing cells in en>sSpitz, mCherry:Moesin embryos). These effects were restricted to the anteriormost en stripe located within the Cnc domain. En stripes were visualized by coexpression of mCherry:Moesin (red). (E) Patterned EGF receptor signaling and Cnc activity activate cell alignment, oriented cell division, and apicobasal cell elongation to produce a square cell grid at the midline of the developing pharynx. (F) Uniform Cnc expression or EGFR activity produce an expanded square grid in the region where both signals overlap. Bars, 5 μm.