HES1 and Osteopenia: To determine whether the inactivation of Hes1 could reverse the osteopenia of the Notch2tm1.1Ecan mutation, CtskCre/WT;Hes1loxP/loxP mice were crossed with Notch2tm1.1Ecan;Hes1loxP/loxP mice to inactivate Hes1 in the context of the Notch2 mutation.