FPR3, also known as FPRL2, belongs to the formyl peptide receptor family which includes FPR1, FPR2, and FPR3. Monocytes express FPR1, 2, and 3; upon differentiation into macrophages, expression of these receptors is maintained. Two ligands, humanin and F2L have been identified. Humanin is expressed in the heart, skeletal muscle, kidney, and liver but is not expressed in the immune system. F2L is a heme-binding protein first identified in the spleen. Binding of FPRL2 and F2L induces Ca2+ mobilization and neutrophil chemotaxis. Low level of expression of FPRL2 has also been reported on NK cells.