Elevating APC2 levels increases the ability of endogenous Wg signaling to turn down the destruction complex, thus increasing Arm levels in cells receiving Wg.

<p>(A-D) Fixed Stage 9 embryos. Anterior to the left. (A-C) Representative images, wildtype (A) or Mat GFP:APC2 embryos with higher (B) or lower (C) levels of GFP:APC2 expression. Elevating APC2 levels increases levels of Arm specifically in cells receiving Wg signal. (D) Close-up, embryo expressing elevated levels of GFP:APC2. The boundary of cells with elevated levels of Arm is quite sharp, and does not expand much farther than the cells adjacent to those expressing Wg. (E) Elevating APC2 levels increases Arm accumulation in Wg stripes but does not affect Arm levels in interstripes. Box and whisker plot (as in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007339#pgen.1007339.g004" target="_blank">Fig 4I and 4K</a>), comparing Arm accumulation levels in Wg-expressing stripes versus Arm in the interstripes in wildtype or Mat GFP:APC2 embryos imaged on the same slide. (F) Difference in Arm accumulation between the Wg stripes and interstripes within individual embryos. Each point = a single embryo. (G) Plots of Arm accumulation pattern over 2 segments. Dot plots = raw data from 3 separate embryos. Line graphs underneath = averages of these data. Elevating APC2 levels exaggerates and sharpens the Arm stripes. (H) Immunoblotting with anti-Axin antibodies reveals that embryos overexpressing APC2 have no change in Axin levels. Statistical analysis: a paired t-test was used to assess the significance between intragroup values in E, and an unpaired t-test was used to determine the significance between intergroup values in E and F. A one-way t-test was used to assess the significance of difference in Axin levels in H. ns, not significant i.e. p≥ 0.05. ** = p<0.01. *** = p<0.001. **** = p<0.0001.