Tg(7xStat3:EGFP) is a bona fide Stat3 pathway reporter. (A) Whole mount in situ hybridization detection of EGFP mRNA in the optic tectum of 48 hpf embryos treated with inhibitors of the Stat3 pathway, AG-490 and LLL12; control embryos were treated with DMSO. (A′) Percentage of samples displaying EGFP mRNA expression in the optic tectum (three independent biological samples; n=40). (B) Fluorescent image of Tg(7xStat3:EGFP) intestine at 6 dpf after 3 days of either 60 µM AG-490 or DMSO treatment. (B′) EGFP fluorescence quantification in the intestine of AG-490 and control larvae after 3 days of 60 µM AG-490 administration (n=20). (C) qRT-PCR analysis of stat3, socs3a and EGFP expression in EGFP-positive and EGFP-negative cells taken from adult intestines. (D) Immunofluorescence against mouse Stat3 (red spots) and colocalization with EGFP fluorescence of Tg(7xStat3:EGFP) larvae injected with CMV-mStat3C plasmid. (E) Live image of the intestine of 7 dpf stat3−/−/Tg(7xStat3:EGFP) and stat3+/+/Tg(7xStat3:EGFP) siblings. (E′) EGFP fluorescence quantification in the intestine of wild-type (WT) and stat3−/− Tg(7xStat3:EGFP) larvae at 7 dpf (n=12, P=0.0211). (E″) qRT-PCR analysis of EGFP expression in 7 dpf stat3−/−/Tg(7xStat3:EGFP) larvae with respect to the stat3+/+/Tg(7xStat3:EGFP) sibling (three biological samples). All statistical analyses were performed by unpaired t-test; *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001. Graphs indicate mean±s.e.m. Scale bars: 100 μm (A,B,E), 10 μm (D).