When cell lines are used to produce a biological product, a cell bank system should be used. Particularly in case that your protein of interest will follow clinical studies, regulatory agencies require cell bank manufacturers to guarantee continued stability and safety of cell lines producing biologics under cGMP.
The model of cell banking is applicable to any microbial or mammalian cell line. However, each host or cell bank and to produce each product and with for each intended purpose will require different cell banking generation and characterization activities.
Regulatory agencies will finally determine which tests must be performed based on the production host and the specific product, but typically always including identity, stability and purity.