Clone 4B4-1 is a mouse monoclonal antibody specific to the human gene, TNFRSF9, or TNF receptor superfamily member 9. Another name for the gene is CD137. This antibody clone has been reported to also recognize the primatee ortholog of the target gene. Indicated applications for antibody clone 4B4-1 include flow cytometry, ELISA, and immunoprecipitation.