Expression of GFP and GFPdnLMP1 in transfected carcinoma cells. Transgene negative control cell lines 53.217 and CarbB, and transgenic PyLMP1 cell lines 53.234a and 53.278a, transfected with pGFP or pGFPdnLMP1 were sub-cloned to give clones denoted GFP and dnL (respectively). Protein samples from each cell line sub-clone (indicated by -number) or pool of clones (-p) were examined by western blotting, sequentially using anti-LMP1 (top of each panel), α-GFP (middle) and α-beta-tubulin (bottom), as indicated. (A) 100 μg of protein extract from sub-clones or pools of clones from the cell lines 53.217, CarB and 53.234a. (B) and (C) 50 μg protein extract from sub-clones or pools of clones (pI and PII) from the cell lines 53.278a and control CarB. Non-transfected parental cell line (nt).