You have learned that GDI is an important regulator of small GTPases, but its function in cell migration is not clear. A wound healing assay shows that expression of high GDI levels produces defects in cell migration. To evaluate actin organization in these cells, you have expressed GFP-tagged actin and observed that actin organization at the leading edge of the cell is normal, but that there are significantly fewer stress fibers in the cell body and at the trailing edge of the cell.Which of tollowing answer is most consistent with your observation? a. GDI overexpression reduces the cytosolic concentration of G-actin ATP so that F-actin is rapidly depolymerized. b. GDI overexpression stimulates the activity of Rho, which then binds to the actin nucleation protein formin to nucleate linear actin filaments. c. GDI prevents a chemoattractant in the medium to bind to the receptor so that migration cannot occur. d. GDI sequesters the small GTPase Rho in the cytosol so that it cannot be activated by its GEF. e. GDI blocks the activation of Rac at the leading edge of the cell.
