  We study the evolution of the (e,e'p) cross section on nuclei with increasing
asymmetry between the number of neutrons and protons. The calculations are done
within the framework of the distorted-wave impulse approximation, by adopting
nonrelativistic and relativistic models. We compare the results obtained with
three different approaches based on the mean-field description for the proton
bound state wave function. In the nonrelativistic model phenomenological
Woods-Saxon and Hartree-Fock wave functions are used, in the relativistic model
the wave functions are solutions of Dirac-Hartree equations. The models are
first tested against experimental data on $^{16}$O, $^{40}$Ca, and $^{48}$Ca
nuclei, and then they are applied to calculate \eep cross sections for a set of
spherical calcium and oxygen isotopes. From the comparison of the results
obtained for the various isotopes we can infer information about the dependence
of the various ingredients of the models on the neutron to proton asymmetry.
