How do I label an animal cell?

The best way to label an animal cell is with fluorescent dyes. Here’s the step-by-step process you need to use for labeling an animal cell using immunofluorescence:

1. Prepare the cells for easy handling by attaching them to a solid support. This can be done in a couple of different ways. One way is to grow adherent cells on an optically suitable plastic support, microscope slides, or coverslips. Another way is to centrifuge suspension cells onto glass slides or use chemical linkers to bind them to solid support.  
2. Fix and permeabilize the cells. This ensures that the antibody has free access to its antigen. The fixation method you choose- organic solvents or cross-linking reagents - will depend on the properties of the antibody and antigen used. Organic solvents such as acetone and alcohols eliminate lipids, dehydrate the cells, and precipitate proteins on the cellular architecture. 
1. Cross-linking reagents such as paraformaldehyde, create a network of linked antigens by forming intermolecular bridges through free amino groups. The advantage of this method is that it preserves the structural integrity of cells better than organic solvents. On the other hand, it reduces the antigenicity of some cellular components. If you use cross-linking reagents, you may need to add an extra permeabilization step to allow the antibody to access the antigen. 
3. Incubate cell preparations with the primary antibody. Wash the sample to remove the unbound antibody. If the primary antibody is labeled, you can detect the bound antibody directly, otherwise you can detect it indirectly using a fluorochrome-labeled secondary reagent.
4. Assess the staining. Use fluorescence microscopy to evaluate the staining and identify the presence and subcellular localization of the antigen.