Competition for growth factors: A lot more death with a little less Aktion

摘要

Apoptosis is frequently seen in response to cytotoxic drugs or other stimuli that provoke cell damage or stress. However, the vast majority of homeostatic cell deaths in vivo occur due to physiological cues that permit the selection of the fittest cells within a tissue, by weeding out the aged and the superfluous through competition. One such fitness test is competition for growth factors. Raff championed the idea of social control of cell death by predicting that all cells continuously require signals (i.e., growth factors) provided by other cells to maintain viability.1 The failure to compete successfully for growth factors not only prevents cell division but also can lead to the generation of signals that eliminate cells via apoptosis. However, despite the importance of this topic, it still remains unclear precisely how growth factor receptor engagement, or lack thereof, interfaces with the cell death machinery.