  We study the correlation between proton lifetime and leptonic CP violation in
a class of renormalizable supersymmetric SO(10) grand unified theories (GUTs)
with {\bf 10}, {\bf 126} and {\bf 120} Higgs fields, which provides a unified
description of all fermion masses and possibly resolution of the strong CP
problem. This specific model is unique in that it can readily be compatible
with current proton lifetime limits for a supersymmetry (SUSY) breaking scale
as low as 5 TeV due to the presence of a specific Yukawa texture. Our
investigation here reveals that proton partial lifetimes predicted by this
class of models will be tested by forthcoming proton decay searches;
furthermore, a discovery of leptonic CP violation in neutrino oscillations
would also lead to substantial reduction of the parameter space of the model.
