FIGURE 23-31 Signal transduction from the T-cell receptor (TCR) and B-cell receptor (BCR). The signal transduction pathways used by the antigen-specific receptors of T cells (left) and B cells (right) are conceptually similar. The initial stages are depicted in this figure; downstream signaling events lead to changes in gene expression that result in proliferation and differentiation of the antigen-stimulated lymphocytes. See text for further discussion.