We have also shown how and why oncogenic mutants of Ras cannot be stimulated by RasGAPs. We have studied the kinetics of interaction of Cdc25, a RasGRF homologue, with Ras. Although it has recently been shown to activate integrins, its exact biological role and the signal transduction pathways that it is involved still need to be defined. Rap and GEFs Rap is activated in the cell by a number of signal transduction pathways, using a variety of GEFs. Preliminary experiments on conserved residues suggests that indeed RapGAP does not work via an arginine finger mechanism.
Studies are ongoing to explore the catalytic mechanism.
They are also necessary for Ras-induced cell transformation. The other is PAK, for p21-actived protein kinase, which contains a catalytic and regulatory domain. Both organisms apparently use the properties of Rho proteins to modulate the properties of host cells for their infection and we are working on the molecular mechanism of their action.