I am working to express my protein in HMVEC cells with lentiviral transfection system. I used 293T cells as the virus producing cells and I can detect my protein with western blot from the 293T cell lyste. However, I don't see any band from my HMVEC cells even with immunoprecipitation. I also used QPCR to detect mRNA expression and I can see overexpression of my target gene. My protein is Myc-tagged, and coexpressed with GFP. I used flow sorting to select GFP cells to enrich the transfected population. Is the protein degraded in HMVEC cells? Is there anyway to find out the problem from transcription to translation in this cell?

Thank you!