  We analize the influence of nuclear effects on the determination of the
nucleon axial mass from nuclear cross sections. Our work is based on a
formalism widely applied to describe electron-nucleus scattering data in the
impulse approximation regime. The results of numerical calculations show that
correlation effects, not taken into account by the relativistic Fermi gas
model, sizably affect the $Q^2$-dependence of the cross section. However, their
inclusion does not appear to explain the large values of the axial mass
recently reported by the K2K and MiniBooNE collaborations.
