Huang et al. have recently reported the role of EZH2 destabilization through heat shock protein (Hsp) 90 inhibition, independent of histone methylation in various GvHD mouse models as a pathway for reducing GvHD [23], further questioning the role of EZH2/PRC2-mediated histone methylation in alloreactivity. The gene discussed is EZH2; the disease is graft versus host disease.