Multiple signals from the TCR, co-stimulatory receptors, cytokines, growth factors, nutrients (amino acids, glucose, and nucleotides), oxygen, and DNA damage tune mTOR activation in T cells. In this figure, positive regulators are shown in ovals, and negative regulators are shown in squares; genes whose effects have been studied in genetic deletion systems are in red. Black solid arrows indicate an activating event, and black flat-ended arrows indicate an inhibitory event.