P2RX7 and graft versus host disease: Collectively, this data supports the role of extracellular ATP (Geraghty et al., 2019d) and the subsequent activation of the P2X7 receptor (Geraghty et al., 2017; Geraghty et al., 2019c) in promoting GVHD, most notably liver GVHD, in this humanized mouse model.