Hi Giuseppe,

if it isn't too much difficulty, could you maybe start by adding a small epitope tag such as C-terminal myc or HA?  Then you could at least detect the protein by Western Blotting.  I appreciate that this involves modifying the sequence and I guess that you are using the endogenous message judging by what you have written above, but this is the only way I can think of to establish that the message itself is being translated into your expected protein.

Best of luck,  Robin

Hi there,

Why do you absolutely want to label the protein? If expression is good you would be able to spot the corresponding band on SDS/PAGE(provided you run the suitable negative control in parallel)  and characterize it by MS.

Dear Robin and Dominique.

Thank you so much for your response.

Yes, both cloning the CDS upstream a flag and MS after SDS-PAGE/Coomassie Staining are in the "to do" list. 

Thanks again for your willing in helping me out.