Pho behaves similarly to and differently from Pc with respect to Myc activity. For all scatter-plot graphs, the diagonal blue lines indicate zero change and 2-fold changes in either direction. Our thresholds for labeling genes as increasing or decreasing are not based on fold changes (see Methods), and therefore the locations of the colored dots may or may not correspond to a 2-fold change in expression. (A) Results of genetic manipulations. The log2 ratios of normalized intensities are graphed for each manipulated gene in each manipulated embryo. The left-most set of bars are from embryos expressing ectopic dmyc, and each bar shows the change in Pc, pho, ash1 and dmyc levels, respectively, in those embryos compared to embryos with just Gal4 (log2 (intensity Gal4 dmyc/intensity Gal4)). The next set of bars shows the changes in Pc, pho, ash1 and dmyc in embryos with ash1 RNAi, and so on. The genetic manipulation is indicated above each set of 4 bars. (B) Expression levels of 8865 genes are plotted by their basal levels along the X axis and their levels upon expression of ectopic Myc along the Y axis. Genes repressed by Myc are shown in red, n = 57. (C) Pc and Pho are required for Myc repression of half its targets. Expression changes, represented as log2 of ratios of expression over basal, of 55 Myc repressed transcripts are shown with changes with ectopic Myc (blue bar) next to their expression changes with ectopic Myc and Pc RNAi combined (red bar, top), or ectopic Myc and pho RNAi combined (red bar, bottom). The same 55 genes are graphed in the same order in both the upper and lower panels. (D) Expression levels of 8865 genes are plotted by their basal levels along the X axis and their levels upon pho RNAi along the Y axis. Red dots indicate genes whose levels rise with pho RNAi alone, blue dots indicate genes whose levels rise with Pc RNAi alone, and purple dots indicate genes whose levels rise with each of Pc or pho RNAi. (E) Expression levels of 8865 genes as in D, showing changes with ectopic Myc. Blue dots indicate genes whose levels rise with ectopic Myc. Red dots indicate genes whose levels rise with pho RNAi, purple indicates genes whose levels rise in each of ectopic Myc and pho RNAi.