Innate immune recognition of S. pneumoniae by tissue-resident alveolar macrophages or epithelial cells stimulates the production of pro-inflammatory C-X-C motif chemokine ligand 1 (CXCL1) and CXCL2, which recruit and activate cells, such as monocytes, macrophages, and neutrophils to the site of infection (27–29). The gene discussed is CXCL2; the disease is infection.