 These enzymes are activated by IL-2 binding to the external domains of the IL-2R.As a consequence, three intracellular signaling pathways are initiated, the MAP kinase pathway, the Phosphoinositide 3-kinase (PI3K) pathway, and the JAK-STAT pathway.Once IL-2 binds to the high affinity receptor, the complex is rapidly internalized and has only a short time to signal.