To determine whether naive and therefore antigen-inexperienced T cells in RA patients show evidence of increased constitutive activation compared to those from healthy control (HC), we quantified Y128 phosphorylation of SLP76, a proximal scaffolding molecule phosphorylated by the ZAP-70 kinase immediately downstream of TCR stimulation, in freshly separated peripheral blood mononuclear cells (PBMCs). The gene discussed is LCP2; the disease is rheumatoid arthritis.