Figure 6.

ETV5-RFP reports FGF10/FGFR2b signaling in vitro (A) E12.5 Etv5^RFP lungs were harvested and cultured with (experimental) or without (control) 5 μg/ml recombinant (soluble) FGFR2b for 48 h. Scale bar: (Top rows) 500 μm; (Boxes) 125 μm. (B) Left lobe distal tips show arrested branching in experimental lungs after 24 h. FGF10/FGFR2b inhibition, compared to control lungs. While both control lungs and experimental lungs had a similar number of average tips at 0 h, only control lungs showed an increase in branching over time (Data are presented as mean with 95% CI; ^**p < 0.01). (C) RT-qPCR analysis of the lungs showing downregulation of RFP, Etv4, and Etv5, in experimental lungs, demonstrating the usefulness of the Etv5^RFP line to report FGF10/FGFR2b signaling. Note, we only had one control Etv5^RFP lung and two experimental Etv5^RFP lungs, thus statistical analysis was not possible (Data are presented as mean ± SEM; ^**p < 0.01).