Fig 10.

Graphic representation of the contrasting roles of SOS in activating the ERK pathway versus the p38 pathway. ERK activation is bimodal and sharply thresholded. These characteristics critically rely on allosteric activation of SOS. In contrast, p38 activation is not sharply thresholded. Whereas optimal p38 activation does require the presence of SOS1, it does not depend on allosteric activation of SOS1, on an intact RasGEF domain, or on an intact DH domain. These results suggest that SOS1 has an adaptor function in the p38 pathway. Graphic design by Anna Hupalowska.