  We consider non-compact Z_N orientifold models of type IIB superstring theory
with four-dimensional gravity induced on a set of coincident D3-branes. For the
models with odd N the contribution to the one-loop renormalization of the
Planck mass is shown to come only from the torus and to be O(N) as the
contributions from annulus, Moebius strip and Klein bottle cancel. One can
therefore realize the Dvali-Gabadadze-Porrati idea that four-dimensional
gravity is induced by quantum effects at the one-loop level by considering
large N.
