Can I loose the protein of interest from a stable clone? - (Dec/15/2014 )

hi,

Iam facing a weird problem after transfection. I am using C3H10 meschencymal cell line which is a stable clone expressing a protein which is GFP tagged. Iam using this cell line to transfect another protein having a red tag. both the protein has G418 resistance. After a month, I have few colonies. But when I see it under the fluorescent microscope the resistant cells neither have GFP or red tag.

1 . How is this possible,  when I have used a stable clone with a GFP protein ( I did check the cell for fluorescence before the experiment.) for transfection.

2. Do the cells loose the protein for any reason.

Suggestions are welcome

Are GFP and NeoR under different promoters, or do you have a P2A sequence between? I would also suggest to not have the same resistance gene on both of your tags.

Let me check this. Never thought of this before