Programmed cell death protein 1 (PDCD1) is an immune-inhibitory receptor which delivers inhibitory signals upon binding to ligands CD274/PDCD1L1 and CD273/PDCD1LG2, playing a critical role in induction and maintenance of immune tolerance to self. PDCD1 plays a role in anti-tumor immunity and is involved in safeguarding against autoimmunity, but PDCD1-mediated inhibitory pathway is also exploited by tumors to attenuate anti-tumor immunity. PD-1 Protein, Canine (Biotinylated, HEK293, His-Avi) is the recombinant canine-derived PD-1 protein, expressed by HEK293 , with C-Avi, C-His labeled tag.