There are several indications that an opaque partonic medium is created in energetic Au+Au collisions (\sqrt{s} ~ 100 GeV/nucleon) at the Relativistic Heavy Ion Collider (RHIC). At the extreme densities of ~10-100 times normal nuclear density reached even heavy-flavor hadrons are affected significantly. Results on heavy-quark observables will be presented based on the parton transport model MPC, focusing on the nuclear suppression pattern, the azimuthal anisotropy (elliptic flow), and azimuthal correlations. I will contrast the opacities extracted from various light and heavy-flavor observables and will test whether both open and hidden heavy-flavor can be understood quantitatively in the parton transport framework.