In line with the reduced levels of antigen-induced arthritis in Vav1–/– mice, we also found using quantitative RT-PCR that the expression of transcripts encoding cytokines involved in the regulation of different immune cell types that participate in the deterioration of the joint tissue is totally eliminated (in the case of Tnfa, Ifng, Il1b) or highly reduced (in the case of Il6 and Il17) in the mBSA-injected joints of Vav1–/– mice (Figure 2B). This evidence concerns the gene IL1B and arthritic joint disease.