CCL23, also known as MIP 3, is a small cytokine which belongs to the CC chemokine family. Cytokines are a family of secreted proteins involved in immunoregulatory and inflammatory processes. CCL23 is predominantly expressed in lung and liver tissue, but also can be detected in bone marrow and placenta. It displays chemotactic activity on resting T lymphocytes and monocytes, lower activity on neutrophils and no activity on activated T lymphocytes. CCL23 is also a strong suppressor of colony formation by a multipotential hematopoietic progenitor cell line.