Probable hormone (Probable). Promotes chemotaxis in myeloid cells (By similarity). Homodimer. Heterodimer with RETNLB. Highly expressed in bone marrow, spleen and white blood cells. Also detected at low levels in thymus, lung, trachea, white adipose tissue, nasal respiratory epithelium, colon, small intestine, kidney, liver, and heart. Belongs to the resistin/FIZZ family.