Figure 4.

FGF signaling altered primary cilia via ERK and mTORC2 signaling. (A) NIH3T3 cells were treated with chemical inhibitors of MEK kinase (PD0325901), mTORC1/mTORC2 (AZD3147), PI3K (PI828) and mTORC1 (rapamycin) for 1 h prior to FGF2 treatment for 10 min. Inhibitor activity was confirmed by detection of phosphorylation (p) of targeted molecules in each inhibited pathway (indicated in red). Actin served as loading control. (B) NIH3T3 cells were treated with inhibitors and FGF2 for 12 h, the cilia were immunostained for ARL13B and their lengths were measured and plotted. Note that the inhibition of ERK pathway partially rescued FGF-mediated cilia elongation. Similar effect was achieved by mTORC1/mTORC2 inhibitor AZD3147. Rapamycin and PI828 showed no effect on FGF-mediated cilia elongation. (C) Published IC₅₀ values for the inhibitors used.