Lyophilized solid. Lyophilized from sterile-filtered PBS. AVOID FREEZE/THAW CYCLES. Recombinant, human 4-1BB (amino acids 24-186) fused to the Fc portion of human IgG₁ via a polylinker and expressing a His•Tag^® sequence. The chimeric protein, expressed in the mouse myeloma cell line NSO, is a disulfide-linked homodimeric glycosylated protein. Migrates at ~50-65 kDa in SDS-PAGE under reducing conditions. Biological activity: Blocks the T-cell co-stimulatory activity of the agonist anti-4-1BB antibody.. Purity: ≥95% by SDS-PAGE. Contaminants: Endotoxin: ≤0.1 ng/µg 4-1BB/Fc Chimera.