Before revision:  Thus, mutations disrupting this equilibrium beyond the protein marginal stability upper bound ( 7.4 kcal/ mol) will be subject to negative selection and mutations that preserve it will be neutral or nearly neutral , with respect to the marginal stability. Although, proteins can still evolve under the influence of natural selection .
After revision:  Thus, mutations disrupting this equilibrium beyond the protein marginal stability upper bound ( 7.4 kcal/ mol) will be subject to negative selection and mutations that preserve it will be neutral or nearly neutral , with respect to protein stability, a universal phenomenon .