  In this study we incorporate the Sudakov form factor into the dipole
factorization formula, where the hard scale of the former is provided by the
photon virtuality $Q^2$. We obtain a general formula which we then apply to the
well-known GBW and BGK saturation models. Parameters of the above
Sudakov-improved models are successfully fitted to the $F_2$ data from HERA. We
observe, in particular, that inclusion of the Sudakov factor on top of the GBW
model improves description of data at large $Q^2$.
