Fig. 1.

Signals, signaling pathways, signaling intermediates, cytokines, and transcription factors involved in the differentiation of short-lived (senescent) effector cells and long-lived memory T cells and their positive involvement in the phases of the immune response. Colors are related to the Signal 1, 2, and 3 that initiate T cell differentiation in the priming phase, yellow, red, and blue, respectively. Brown applies to molecules activated by Signal 1 and 2. Green corresponds to activation via Signals 1, 2, and 3