Left: Analysis of GFP expression (green) in transfected HEK293 cells by Immunocytochemistry. Cells were stained with rabbit anti-GFP antibody (red, 1:2,000). Blue: Hoechst staining for nuclei. Transfected cells appear orange-yellow due to the green (GFP) and red (anti-GFP antibody) color overlay. Right: Western blot analysis of GFP protein in transfected HEK293 lysate using rabbit antibody to GFP (green, 1:2,000).  protein standard,  non-transfected control cells,  transfected cells with GFP construct,  transfected cells with mCherry construct. A strong band at ~27 kDa corresponds to the expected molecular weight of GFP protein detected only in cells transfected with GFP construct. The antibody does not cross-react with mCherry protein. The same blot was simultaneously probed with a mouse antibody to beta-tubulin (red, ~ 50 kDa, lanes 2-4).