Take the bus to the "Gare St Charles" train station (every 20 min). There, go down to take SUBWAY line 2, direction "Ste Marguerite Dromel". Get off at the "Rond Point du Prado" station. Your subway ticket is valid for the bus. Take the bus line 21 to "Luminy", or the JetBus that is quicker (only during scolar periods).