Fig 5.

IKK suppresses ASK1-mediated functions. (a) IKK activation inhibits ASK1ΔN-mediated neurite outgrowth. PC12 cells, cultured in the presence or absence (induction of ASK1ΔN) of tetracycline, were treated with TNF-α (10 ng/ml) and/or PS1145 (10 μM) as indicated. After treatment, cells were fixed and stained with phalloidin. (b) Quantification of neurite outgrowth in panel a. (c) COS7 cells were transfected with HA-ASK1 WT, HA-ASK1 S967A, or the catalytically inactive HA-ASK1 K709R and serum starved (24 h). Caspase-3 activity was measured as pmol of p-nitroaniline released/h/μg of protein. The first bar indicates activity of the blank. The data represent means plus the the standard deviations (n = 3). pS967 ASK1 and total protein levels were detected by Western blotting. (d) Model of ASK1 regulation by IKK.