These experiments showed that TLR4 expression in the stroma was necessary and sufficient to trigger emergency granulopoiesis in response to LPS. Tie2-cre:Myd88fl/fl mice, which lack MyD88 in hematopoietic and endothelial cells, are unable to induce emergency granulopoiesis after LPS treatment or Escherichia coli infection indicating that TLR4 signaling in endothelial cells orchestrates emergency granulopoiesis. The gene discussed is TLR4; the disease is escherichia coli infection.