MSH2 and cerebral cavernous malformation: Although CCM lesions in the sensitized model faithfully recapitulate defining characteristics of human CCM lesions, a potential confounding variable is the propensity of mice with genetically unstable backgrounds to develop tumors: Msh2-/- mice develop lymphomas around two months and Trp53−/− mice develop neoplasms by six months [90,91,92].