User guide

Assessing productivity
Protein production
To check for production of your protein during stable cell establishment, you may
take an aliquot of growth media and perform SDS-PAGE, protein-specific ELISA,
or the bioactivity assay of choice to determine that your cells are producing your
protein of interest.
IMPORTANT!
When you have a pool of stably-transfected cells, freeze several aliquots of the
pool using the procedure on page 18.
Choosing a
workflow
At this stage you will have a population of stably-transfected CHO DG44 Cells
expressing your protein of interest at various levels. For most bioproduction
applications, several clonally-derived cell lines producing your protein are
desirable for screening. However, the productivity of each clone depends upon
the integration locus of the plasmid(s), the response to amplification using MTX,
and the nature of the protein.
Depending on your protein production needs, the time and effort required to
generate clonal, high-producing cell lines also vary. Several common pathways
from stable pool to clone scale-up are outlined below. Note that the times shown
for various experimental steps are approximations, and the actual times will
depend on your protein of interest and the specific workflows you choose.
Continued on next page
53