FIG. 2.

Cellular stress response to external stressor (S) may involve both transcriptional (outer solid lines) and posttranslational control (inner dotted lines) of the cellular state (Y). The transcriptional induction of stress genes (g) is activated by transcription factor (T) either through feedback (bottom arm) or feedforward (top arm). Posttranslational control bypasses the slow-acting transcriptional loops by regulating the activities of preexisting molecules of stress proteins (G) through covalent modifications or other fast mechanisms (dotted lines). Pointed arrows denote activation and blunted arrows denote inhibition.