HMOX1 and graft versus host disease: To explore the regulatory effects of hPMSCs on the Nrf2 signaling pathway in GVHD, considering the existence of the crosstalk between Nrf2 and NF-κB, the levels of Nrf2 and downstream target genes (HO-1, NQO1, GCLC, and GCLM) and the phosphorylation levels of NF-κB and I-κB were determined in the liver and spleen tissues of the mouse model.