Proposed model of host signaling cascade in response to microbial signals to promote hematopoiesis. MAMPs activate the TLR pathway, and meso-diaminopimelic acid (DAP) activates the NOD1 pathway in stromal cells. The TLR and NOD1 pathways can cross talk at tumor necrosis factor receptor-associated factor 3 (TRAF3) and induce type I interferon (IFN) production. These type I IFNs can then activate the type I IFN pathway via signal transducer and activator of transcription 1 (STAT1) in HSPCs and activate a gene profile that is necessary to promote hematopoiesis.