STAG2 and cancer: First, we believe that the study of tumor-derived missense mutations provides a particularly useful window into the specific functions of STAG2 that are relevant to cancer pathogenesis, since the adverse effects of missense mutations are likely to more specific to cancer pathogenesis than the more pleiotropic effects of early truncating mutations (with the caveat that it is a formal possibility that a subset of missense mutations are passenger mutations).