JAK2 and graft versus host disease: Beyond its antiproliferative impact on the cellular level, Ruxo also exerts immunosuppressive effects due to the integral function of JAK2 and its paralog JAK1 in cytokine networks, which are exploited clinically for the treatment of graft-versus-host disease (GvHD) following allogenic hematopoietic stem cell transplantation (36, 37).