What are the applications of Mammalian Expression?

Question

Mammalian expression systems are the ideal choice to produce eukaryotic proteins as they are able to introduce proper protein folding, post-translational modifications, and product assembly. Although the yeast, insect and other eukaryotic cell also has the modification of glycosylation, the way of glycosylation is different from that of the human and the other mammalian cell does. Proteins expressed in mammalian cells are nearly the same with the nature proteins in the term of structure, glycosylation style and the way of glycosylation, and can be assembled into multi-subunit protein.