Ras and Rap proteins are closely related small GTPases. Whereas Ras is known for its role
in cell proliferation and survival, Rap1 is predominantly involved in cell adhesion and cell
junction formation. Ras and Rap are regulated by different sets of guanine nucleotide
exchange factors and GTPase-activating proteins, determining one level of specificity. In
addition, although the effector domains are highly similar, Rap and Ras interact with largely
different sets of effectors, providing a second level of specificity. In this review, we discuss …