  Discovery of neutrino mass has put the spotlight on supersymmetric SO(10) as
a natural candidate for grand unification of forces and matter. However, the
suppression of proton decay is a major problem in any supersymmetric grand
unified models. In this paper we show how to alleviate this problem by simple
threshold effect which raises the colored Higgsino masses and the grand
unification scale to \gtrsim 10^{17} GeV. There exist only four types of fields
arising from different SO(10) representations which can generate this kind of
threshold effects. Some of these fields also generate a sizable flavor
violation in the quark sector compared to the lepton sector. The b-\tau
unification can work in these types of models even for intermediate values of
tan\beta.
