Patent ID: 8569054

Claim:
A method of producing a mammalian cell line that is pre-adapted for growth and transfection in serum-free medium comprising: a) transfecting a mammalian cell line with a first nucleic acid encoding a mutant Bcl-2 protein comprising T69E, S70E and S87E amino acid substitutions, to produce a Bcl-EEE host cell; b) culturing the Bcl-EEE host cell in the presence of methotrexate to amplify the first nucleic acid; and c) adapting the Bcl-EEE host cell to grow in serum-free medium to produce a pre-adapted Bcl-EEE host cell, wherein the pre-adapted Bcl-EEE host cell can be transfected in serum-free medium with a second nucleic acid encoding a recombinant protein.