  The radion scalar field might be the lightest new particle predicted by
extra-dimensional extensions of the Standard Model, thus possibly leading to
the first signatures of new physics at the LHC. We perform a study of its
production in association with a $Z$ boson in the custodially protected warped
model with a brane-localised Higgs boson addressing the gauge hierarchy
problem, with Higgs-radion mixing effects included. While the considered radion
production at the LHC would constrain some parts of the parameter space, it is
only the ILC program that will be able to cover a significant part of this
space through the studied process. Complementary tests of the same theoretical
parameters can be realised through the high accuracy measurements of the Higgs
couplings at ILC.
