FIGURE 4.

Depletion of subunits from ESCRT-0, -I, -II, or -III attenuates phosphorylation of Akt upon CXCR4 activation. A–D, depletion of individual subunits from each of the ESCRT complexes attenuates CXCR4-promoted Akt activation. HeLa cells treated with siRNA directed against STAM1 (ESCRT-0), UBAP1 (ESCRT-I), Vps22 (ESCRT-II), CHMP4C (ESCRT-III), or luciferase (Ctrl) were serum-starved for 3 h followed by treatment with vehicle (minus symbol) or CXCL12 (plus symbol) for 5 min, as described under “Experimental Procedures.” Equal amounts of whole cell lysates were immunoblotted for the indicated proteins and their phosphorylation status. Representative blots from four independent experiments are shown. V, vehicle; S, CXCL12; E, EGF; and I, insulin.