Mitocryptide-2, a neutrophil-activating cryptide, is a specific endogenous agonist for formyl-peptide receptor-like 1

► The cryptides, functional cryptic peptides hidden in protein structures, have become a topic of interest for the global scientific community. ► Mammalian N-formylated cryptide MCT-2 which is derived from mitochondrial cytochrome b induced neutrophil activation at nanomolar concentrations. ► MCT-2 is a specific endogenous agonist for FPRL1 which is proposed to play key roles in inflammatory responses but whose physiological agonists are equivocal. ► MCT-2 was shown to promote neutrophilic function as a consequence of Gi- or Go-type G protein-dependent intracellular signaling events including [Ca2+]i increase and phosphorylation of ERK1/2.