  We reexamine cosmological applications of the holographic energy density in
the framework of sourced Friedmann equations. This framework is suitable
because it can accommodate a macroscopic interaction between holographic and
ordinary matter naturally. In the case that the holographic energy density
decays into dust matter, we propose a microscopic mechanism to generate an
accelerating phase. Actually, the cosmic anti-friction arisen from the decay
process induces acceleration. For examples, we introduce two IR cutoffs of
Hubble horizon and future event horizon to test this framework. As a result, it
is shown that the equations of state for the holographic energy density are
determined to be the same negative constants as those for the dust matter.
