Abstract: The present invention describes new mammalian expression vectors comprising a novel combination of regulatory elements and one or more selection marker gene(s). The vector allows for incorporation of at least one, preferably two or more genes of interest, its/their subsequent expression, and for selection of transfected cells using, e.g., G418 and/or MTX. The pDGP?GOI vector as an example for a mammalian expression vector according to the present invention exhibits a 9555 bp sequence, one strand of which is represented by SEQ ID NO:2.

Abstract: The present invention describes new mammalian expression vectors comprising a novel combination of regulatory elements and one or more selection marker gene(s). The vector allows for incorporation of at least one, preferably two or more genes of interest, its/their subsequent expression, and for selection of transfected cells using, e.g., G418 and/or MTX. The pDGP?GOI vector as an example for a mammalian expression vector according to the present invention exhibits a 9555 bp sequence, one strand of which is represented by SEQ ID NO:2.

Abstract: The present invention provides a process for the production of erythropoietin (EPO) with high purity and with a desired profile of EPO glycol-isoforms by using a combination of specific chromatographic steps in such a manner that the starting EPO glycol-isoform profile is changed or modified. The applied chromatographic steps includes at least (a) dye affinity chromatography, and (b) hydrophobic chromatography and/or (c) anion-exchange chromatography. In a preferred embodiment, the process further includes (d) gel filtration chromatography. The present invention also provides a process for the determination of erythropoietin (EPO) glycol-isoform profile in an EPO containing composition.