The CD80 protein plays a key role in T lymphocyte activation, promoting proliferation and cytokine production through CD28 binding. In contrast, interaction with CTLA-4 inhibits T cell activation. B7-1/CD80 Protein, Human (HEK293, His) is the recombinant human-derived B7-1/CD80 protein, expressed by HEK293 , with C-6*His labeled tag.