Fig. 4: Loss of Pax activates EGFR and JAK-STAT signaling.

a–d’ Adult midguts of Esg^ts>Ctrl (a–a’), Esg^ts>Pax RNAi (b–b’), MyoIA^ts>Ctrl (c–c’), and MyoIA^ts>Pax RNAi (d–d’) were immunostained with dpErk (red) and DAPI (nuclei, blue). GFP marks ISCs/EBs/pre-EEs (a–b’) or ECs (c–d’). e Relative mRNA levels of EGFR ligands spi, Krn, and vn were analyzed by real-time PCR. Total RNA was collected from whole midguts of the indicated genotypes: MyoIA^ts>Ctrl, and MyoIA^ts>Pax RNAi (n = 3,3). f–m Adult midguts of Upd-lacZ;Esg^ts>Ctrl (f), Upd-lacZ;Esg^ts>Pax RNAi (g), Upd-lacZ;MyoIA^ts>Ctrl (h), Upd-lacZ;MyoIA^ts>Pax RNAi (i), 10xStat-GFP;Esg^ts>Ctrl (j), 10xStat-GFP;Esg^ts>Pax RNAi (k), Stat-lacZ; MyoIA^ts>Ctrl (l), Stat-lacZ;MyoIA^ts>Pax RNAi (m) were immunostained with β-gal (red), GFP (green) and DAPI (nuclei, blue). Note that Upd and Stat are specifically expressed in precursors. n Relative mRNA levels of JAK-STAT ligands, including Upd, Upd2, Upd3, and target Scos36E were analyzed by real-time PCR. Total RNAs were collected from whole midguts of the indicated genotypes: MyoIA^ts>Ctrl, and MyoIA^ts>Pax RNAi (n = 3,3). Three independent experiments were performed, and the error bars are mean ± SEM. P values of significance (indicated with asterisks, NS no significance P ≥ 0.05, *P < 0.05, **P < 0.01, ***P < 0.001, ****p < 0.0001) were calculated by two-tailed Student’s t-test (e, n). Scale bars: 30 µm. Confocal images were taken from the boundary region between R4c and R5a of the posterior midgut.