View of mixed neuron/glial cultures stained with Chicken polyclonal antibody to Vimentin C-1409-50 (green) and Rabbit polyclonal antibody to Glial Fibrillary Acidic Protein R-1374-50 (red). Vimentin is expressed alone in fibroblastic and endothelial cells, which are the flattened cells in the middle of the imate which appear green. Astrocytes may express primarily Glial Fibrillary Acidic Protein (GFAP), or GFAP and vimentin, and so appear red (GFAP only) or golden yellow (GFAP and Vimentin). In cells which express both GFAP and vimentin, the two protein assemble to produce heteropolymer filaments.