JAK2 and neoplasm: Nevertheless, the limited tumor burden in thymus and lymph nodes of terminally ill TEL-JAK2;Tcra−/−;Relb−/− and TEL-JAK2;Tcra−/−→Tcra−/−;Relb−/− mice suggests that the RelB-dependent thymic microenvironment favors the expansion of transformed leukemic cells.