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Fig. 4 Ctrip acts downstream of β-catenin in Drosophila.By comparison with control (A, F), RNAi-mediated depletion of Apc1 in ISCs during pupation using the esgts (temperature-sensitive driver) leads to an increase in progenitor cell (green) number in the midgut (R5A region) (B, C, F). Concomitant expression of the Apc1 RNAi construct with the ctrip RNAi construct leads to a significant reduction in progenitor cell number (D, E, F), in contrast with expression of an RNAi construct targeting yellow (B, F). Graphs show mean ± SEM, with all data points represented. Significance was assessed using the one-way ANOVA comparing all genotypes to control (yi2 + Apci), with Dunnett’s multiple comparisons test. N is the number of adult intestines analyzed. p-values for yi2 + Apci versus yi1, wgi + Apci, ctripi2 + Apci, ctripi3 + Apci are <0.0001, 0.9985, <0.0001, <0.0001, respectively. Progenitor cells are marked with esg > GFP (green) and nuclei are marked with DAPI (blue). Scale bar (A–E): 50 μm. G Quantification is shown as the percentage of wing discs of each genotype with decreased ectopic Scar-Sens for H–P. N is the total number of wing discs analyzed from three independent biological replicates. Statistical significance was analyzed by Fisher’s exact test (two-sided). p-values are both <0.0001. H–P Representative confocal immunofluorescence images of constitutively active armS10 and GFP or RNAi constructs targeting ctrip were expressed in the wing pouch of third instar larval wing discs using the vgB-Gal4 driver. Scarlet-Senseless (Scar-Sens, magenta) is a Wingless target gene reporter, ArmS10-Myc (cyan), GFP (green). Scale bar (H–P): 50 μm. Dorsal, top, and posterior, right. H–J Representative confocal immunofluorescence images of vgB-driven armS10 and GFP overexpression in wing pouch, which induces ectopic Scar-Sens positive cells. K–P Representative confocal immunofluorescence images of co-expression of armS10 and RNAi against ctrip, which suppresses ectopic Scar-Sens-positive cells. ****p < 0.0001, p ≥ 0.05 is not significant (ns). Source data are provided in the Source Data file