Formyl peptide receptors (FPRs) 1-3 are class A GPCRs that play critical roles in host defence against infection and in inflammation. They recognise a highly diverse range of endogenous ligands, including bacteria, virus and host-derived peptides, and lipid mediators. FPR1 is expressed on the surface of leukocytes, where its canonical role is in the regulation of immune responses through recognition of microbe-and damage-associated molecular patterns such as N-formyl methionine peptides derived from bacteria and mitochondria. FPR1 has also been reported to be expressed in many different cell types, including a variety of epithelial and cancer cells. In some cases, evidence for the presence of FPR1 is through transcript detection or immunostaining, and biological relevance or role in these non-canonical settings is often unclear.