One is Yip3/PRA1, a protein with GDF activity and without GEF activity, which promotes the dissociation of Rab9 from GDI and facilitates Rab9 insertion on the membrane [42,43]; the other is SidM/DrrA, which retains both GDF and GEF activities and promotes the recruitment of Rab1 to Legionella-containing vacuoles during host-cell infection [44]. Here, PAEP is linked to infection.