Expression of fibroblast growth factor receptor type 1, α isoform, has a dominant inhibitory affect during pulmonary tumor formation. (A) D2.A1 cells were constructed to express a scrambled short hairpin (shRNA; sc or scram) or the #2 shRNA targeting murine fibroblast growth factor receptor type 1 (FGFR1; sh or shFr1). Depletion of endogenous FGFR1 in these cells was rescued with a nontargeted human full-length form of the third (III) extracellular immunoglobulin (III-Ig) domain of the α isoform of FGFR1 (FGFR1-α-IIIc; Fr1-α) or green fluorescent protein (GFP) as a control. These cells (5 × 105) were injected into the lateral tail vein of female BALB/c mice. Shown are representative bioluminescence images of mice from each group at the time of injection (T0) and 25 days later (day 25). (B) Bioluminescent quantification at the indicated time points for the cohorts described in (A). Data are the mean (±SE) thoracic area flux values normalized to the injected values, resulting in the indicated P values (n = 5 mice per group). (C) Survival analysis of the cohorts described in (A) resulting in at least the indicated P value (n = 5 mice per group).