New work shows that activation of the Ras guanine nucleotide exchange factor SOS is dependent upon the membrane density of phosphatidylinositol-4,5-bisphosphate (PIP 2) and GTP-bound Ras. These ...

Indicator species are living organisms that tell us that something has changed or is going to change in their environment. They can be easily observed, and studying them is considered a cost-effective ...