OA-induced TAK1 phosphorylation mediates MKK3 phosphorylation.
A, OA treatment increases endogenous MKK3 phosphorylation. MMC grown
to subconfluence were treated with increasing concentrations of OA for 6 h as
indicated. Cell lysates were subjected to Western blot analysis with
anti-TAK1, anti-p-MKK3/6, and anti-MKK3 antibodies, respectively. B,
OA-induced MKK3 phosphorylation is dependent on TAK1 activation. Wild-type
HA-TAK1 (wt) or kinase-deficient mutant of HA-TAK1 (DN) was
coexpressed with FLAG-TAB1 and V5-MKK3 in MMC and treated with increasing
concentrations of OA for 6 h. Cell lysates were subjected to Western blot
analysis with anti-HA, anti-p-MKK3/6, and anti-V5 antibodies,
respectively.