Fig. 2.

The HIF-1α F99A TOS mutation suppresses trophic signaling between HBE and HELMF. A, top blots: conditional phenotype of HBE cells used to generate conditioned medium for HELMF culture. Rapamycin (100 nM) was used to suppress mTOR signaling. Bottom blots: expression of Flt1 and Flk1 [nascent (150 kDa) and glycosylated (200 kDa) forms shown] in HELMF following 18-h culture in HBE-conditioned medium. Blots are representative of 4 experiments. B: top histogram shows the actin-corrected change in Flk1 protein abundance in HELMF cultured in HBE-conditioned SFM. *P < 0.05, n = 5. Bottom histogram shows the activity of HIF-1α in the HBE used to generate the conditioned medium. Activity is expressed as fold change over empty vector (pRK7) control. *P < 0.05 relative to control group; n = 5. C: sprouting from HELMF spheroids in Matrigel following 48-h culture in medium obtained from the HBE in A. Scale bar: 182 μm. Box plots at bottom show the data distribution of sprout length. (From bottom: 5th percentile, smallest nonoutlier, lower quartile, median, top quartile, 95th percentile. Bars indicate the data range.) *P < 0.05 relative to wild-type transfected control group; **P < 0.001 relative to wild-type rheb-transfected group; n = 4. One-way ANOVA on ranks with Dunn's post hoc test.