Probable hormone (Probable). Promotes chemotaxis in myeloid cells (PubMed:15064728). Homodimer. Heterodimer with RETNLB. Expressed in colon, lung, spleen, pancreas, ileum and bone marrow (at protein level) (PubMed:15834545). In colon, found throughout the crypt and surface epithelium, including goblet cells (at protein level) (PubMed:15834545). Highest expression is observed in bone marrow, spleen and lung, with lower levels in other tissues (PubMed:12782128, PubMed:14733912, PubMed:15064728, PubMed:15834545). Detected at low levels in granulocytes, but not found in monocytes or lymphocytes (PubMed:14733912). Has very weak expression in white adipose tissue (PubMed:12782128). In liver, strongly expressed at 18 dpc and at birth, and then rapidly declines. In pancreas, strongly expressed at birth with decreasing expression after 4 days of age. Also shows strong expression in neonatal gut, lung and heart. Up-regulated in colon and bone marrow in response to a high-fat diet. Also up-regulated in obese mice mutant for the leptin receptor LEPR (db/db genotype). Belongs to the resistin/FIZZ family. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.