  Within the possible least uncertainty on the nuclear incompressibility
$K_{0}$, we examine effects of $K_{0}$ in heavy-ion collisions at intermediate
energies. Based on simulations of Au + Au collision at 400 MeV/nucleon using an
isospin- and momentum-dependent transport model, we find that the
incompressibility $K_{0}$ indeed affects significantly the attainable density
in central regions, and thus the particle productions and/or distributions at
final states, e.g., nucleon rapidity distributions and yields of charged pions.
Nevertheless, through examining the free neutron over proton ratios $n/p$, the
neutron-proton differential transverse and directed flows as well as the
charged pion ratio $\pi^{-}/\pi^{+}$ and its kinetic energy distribution, we
find that these observables are less affected by the uncertainty of $K_{0}$,
but mainly sensitive to the slope of symmetry energy at the saturation density.
We also compare and discuss our results with the corresponding data.
