11 out of the 60 hub genes associated with immunoregulation have not been studied in GVHD, including Rgs1, Fpr2, Ppbp (Cxcl7), S1pr3, Npy, Hebp1, Kng1, Plg, Cxcl16, Ccl9, and Cxcl3. The PPI network among the 11 genes was constructed (Figure S3A). This evidence concerns the gene FPR2 and graft versus host disease.