Rap1-mediated integrin activation. Talin-mediated activation of β2 integrins requires Rap1 and RIAM expression. A RIAM-Rap1 complex targets talin to the plasma membrane and contributes to conformational activation of talin, resulting in β2 integrin tail binding and integrin activation. Activation of platelet αIIbβ3 is talin and Rap1 dependent but independent of RIAM. The relevant Rap1 effector is yet to be identified. RIAM dependency of α4β1 activation is cell-type dependent (not shown). For clarity, additional proteins contributing to Rap-dependent and -independent integrin activation are not depicted. Professional illustration by Patrick Lane, ScEYEnce Studios.