Flynn et al have demonstrated that Syk signaling within allogeneic B cells contributes to murine cGVHD and can be successfully targeted with TKI therapy. The effect was most dramatic in a model of bronchiolitis obliterans, which is a devastating complication of allogeneic hematopoietic cell transplantation (HCT). Because Syk inhibition holds promise for the treatment of multiple hematologic malignancies, targeting this pathway represents an exciting new intervention to improve both the safety and the efficacy of allogeneic HCT. Professional illustration by Patrick Lane, ScEYEnce Studios.