Immunological technique used to detect a protein. Following the acquisition of a sample of our choice (from cell cultures or animal tissue or human), it's applied on a gel electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis, SDS-PAGE). The pores of the gel allow separation of proteins by their molecular weight. Proteins migrate down in gel through an electric current (hence the term electrophoresis).
The proteins in the polyacrylamide gel are then transferred to a membrane. This support is more appropriate for the immunologic detection. This membrane is then incubated with an antibody specific to our protein of interest. This antibody is then linked to a second antibody, itself coupled with an enzyme. The addition of a chemoluminescent substrate allow to view the presence of bands representing the protein on a X-ray film or by a camera.