Before revision:  We prove optimality in terms of mean first passage times for three different, frequently encountered intracellular transport tasks: i) the narrow escapeproblem (e.g. transport of cargo to a synapse or other specific region of the cell membrane, ii) reaction kinetics enhancement (e.g. binding of a mobile particle with a immobile or mobile target within the cell, iii) the reaction-escape problem (e. g. release of cargo at a synapse after intracellular vesicle pairing. The results indicate that living cells realize optimal search strategies for various intracellular transport problems  economically through a spatial URLanization that involves  only a narrow actin cortex rather than a cell body filled with randomly oriented actin filaments.
After revision:  We prove optimality in terms of mean first passage times for three different, frequently encountered intracellular transport tasks: i) the narrow escapeproblem (e.g. transport of cargo to a synapse or other specific region of the cell membrane, ii) reaction kinetics enhancement (e.g. binding of a mobile particle with a immobile or mobile target within the cell, iii) the reaction-escape - can be minimized with a directional distribution that is reminiscent of the URLanization of the cytoskeleton filaments of cells with a centrosome: radial ballistic transport from center to periphery and back, and ballistic transport in random directions within a concentric shell of thickness \Delta_{\rm opt that living cells realize optimal search strategies for various intracellular transport problems  economically through a spatial URLanization that involves only a narrow actin cortex rather than a cell body filled with randomly oriented actin filaments.