Figure 4.

KLΔ9 mutant showed similar function as KL WT in downstream pERK signaling. HEK 293 cells transiently transfected with FGFR1c and either KL WT or KLΔ9 were treated with 10 ng/mL FGF23 for 30 min to activate FGFR1c signaling. (A) Representative western blot showing differences in ERK phosphorylation compared to total expression of ERK after transfection of KL WT or KLΔ9. Lanes 1 and 2 are negative controls without KL, and lanes 7 and 8 are positive controls with bFGF. The antibodies used are indicated. (B) Bar graph depicting no change in ERK phosphorylation normalized to total ERK expression (error bars are ±SEM; n = 3) when comparing KLΔ9 to KL WT. (C) Same experiments as in panel A with 0, 10, 20, 30, and 45 min time points for ERK phosphorylation kinetics analysis. (D) Statistical analysis of the results from panel C. The intensities of the pERK bands were normalized to that of the total ERK bands from 3 independent experiments. (E) FGF23 dose–response experiments. Similar experiments as those in panels A and C, with different doses of FGF23 for 10 min as indicated. (F) Statistical analysis of the results from panel E. Error bar indicates standard deviation. Significance of results was determined using Student’s t-test: *, p < 0.05.