  We determine the mass of the charm quark ($m_c$) from lattice QCD with two
flavors of dynamical quarks with a mass around the strange quark. We compare
this to a determination in quenched QCD which has the same lattice spacing (0.1
fm). We investigate different formulations of the quark mass, based on the
Vector Ward Identity, PCAC relation and the FNAL heavy quark formalism. Based
on these preliminary results we find no effects due to sea quarks with a mass
around strange.
