  We establish a reformulation of the Connes embedding problem in terms of an
asymptotic property of factorizable completely positive maps. We also prove
that the Holevo-Werner channels W_n^- are factorizable, for all odd integers n
different from 3. Furthermore, we investigate factorizability of convex
combinations of W_3^+ and W_3^-, a family of channels studied by Mendl and
Wolf, and discuss asymptotic properties for these channels.
