Towards this goal, we study the nature of signals received by T cells during activation and how these signals are chemically decoded to drive complex decisions. Signalling then leads to immediate or sustained cell responses and determines cell fate. We employ state-of-the-art quantitative mass spectrometry-based proteomics and integrate this approach with in vitro and in vivo genetic and pharmacological manipulation of cells. We integrate this knowledge using computational modeling of signaling circuits and molecular structures, to understand the complex signals involved in T cell regulation.