The PathHunter® PD-1/PD-1 Dimerization cell line is a stable, engineered cell line for use in studying drug candidates (small molecules or biologics) targeting receptor-receptor interaction. This cell line enables assessment of ligand (e.g. anti PD-1 antibody) induced dimerization of PD-1/PD-1 receptors. This product uses EFC technology. The cell line included overexpresses PD-1 target protein fused to PK alongside PD-1 target protein fused to EA. Upon ligand-induced dimerization of PD-1/PD-1 , detectable EFC signal is produced. This stable modified cell line is provided as two vials of cryopreserved cells.