  We report that the density profiles of globular cluster (GC) systems in a
sample of 17 early-type galaxies (ETGs) show breaks at the radii where the
gravitational acceleration exerted by the stars equals the galactic
acceleration scale $a_0$ known from the radial acceleration relation or MOND.
The match with the other characteristic radii in the galaxy is not that close.
We propose possible explanations in the frameworks of the $\Lambda$CDM model
and MOND. We find tentative evidence that in the $\Lambda$CDM context, GCs
reveal not only the masses of the dark halos through the richness of the GC
systems but also the concentrations through the break radii of the GC systems.
