The PathHunter CD137 Checkpoint Signaling cell line is a stable, engineered cell line for use in studying drug candidates (small molecules or biologics) targeting signaling checkpoints. This cell line enables assessment of CD137 induced non-canonical NF-κB signaling via detection of NIK stabilization. This product uses EFC technology. The included cell line overexpresses ED-tagged NIK (NF-kappa-B Inducing Kinase) protein as well as untagged CD137. Upon activation of the receptor by its ligand or an antibody, NIK is stabilized, allowing detection of EFC signal when treated with exogenous EA. This stable modified cell line is provided as two vials of cryopreserved cells.