[en] JLab has recently measured F_1 (x) and F_2 (x) structure functions separately as well as studied the difference F_2 (x) - 2 xF_1 (x) (Callan-Gross relation) using electron-nucleus deep inelastic scattering (DIS) in the energy region of 2-6 GeV of the electron beam. Theoretically, it is important to understand nuclear medium effects for a fundamental process eN → eX (N is the nucleon and X is jet of hadrons) taking place with a nucleon bound inside the nucleus. Generally, nuclear medium effects in the DIS region are understood due to shadowing and antishadowing effects, mesonic cloud contributions, Fermi motion and binding energy etc. In the present paper we have studied nuclear medium effects in microscopic model using relativistic nucleon spectral function to describe nucleon momentum distribution. The Fermi motion, binding energy effect and nucleon-nucleon correlations are taken into account using spectral functions. The spectral functions that describe energy and momentum distribution of nucleon is obtained by using the Lehmann's representation for the relativistic nucleon propagator and nuclear many body theory is used to calculate it for an interacting Fermi sea in nuclear matter. A local density approximation is then applied to translate these results to a finite nucleus. We have taken into account pion and rho mesons cloud contributions which are found to have important contribution in the intermediate region of Bjorken variable x. Furthermore, shadowing and antishadowing effects are also taken into account using phenomenological model of Kulagin and Petti. Numerical evaluation have been performed both at the leading order (LO) and next-to-leading order (NLO)