  We study the constraints on gravity scale $M_P$ in extra-dimension
gravitational theory, obtained from gravity-induced processes. The obtained
constraints are subdivided into strong (though not robust) and reliable (though
less strong). The strong constraints can be in principle relaxed due to some
broken gauge symmetries, e.g. family symmetry. The strongest constraint is
given by neutrino oscillations. For different assumptions the lower bound on
$M_P$ is $10^{15} - 10^{18}$ GeV. However, it can be, in principle, reduced by
broken family symmetry. More reliable bounds are due to flavor-conserved
operators or those which change the flavors within one family. These bounds,
obtained using the electron mass and width of $\pi \to e\nu$ decay, are
$1\times 10^5$ GeV and $5\times 10^5$ GeV, for these two cases, respectively.
