S100A1 and infection: The cytokine (i) mobilizes neutrophils to the site of infection via the release of CXC chemokines, (ii) prompts non-hematopoietic cells to secrete HDPs including β-defensins, S100A proteins and histatins, and (iii) reinforces the proinflammatory cascade by synergizing with cytokines such as IL-1 and TNFα.