  We show that there is a non-trivial relationship between the dilaton of IIB
supergravity, and the coset of scalar fields in five-dimensional, gauged N=8
supergravity. This has important consequences for the running of the gauge
coupling in massive perturbations of the AdS/CFT correspondence. We conjecture
an exact analytic expression for the ten-dimensional dilaton in terms of
five-dimensional quantities, and we test this conjecture. Specifically, we
construct a family of solutions to IIB supergravity that preserve half of the
supersymmetries, and are lifts of supersymmetric flows in five-dimensional,
gauged N=8 supergravity. Via the AdS/CFT correspondence these flows correspond
to softly broken N=4, large N Yang-Mills theory on part of the Coulomb branch
of N=2 supersymmetric Yang-Mills. Our solutions involve non-trivial backgrounds
for all the tensor gauge fields as well as for the dilaton and axion.
