Antibody-based detection of sample proteins: A) Protein arrays or reverse phase protein arrays. Proteins are spotted on a support (i.e. glass slide). The primary antibody binds specifically to its protein. The secondary antibody conjugated with HRP (or fluorescence) then bind to the primary antibodies. The substrate is cleaved by HRP to develop detectable color. B) Antibody arrays. Antibodies are spotted on a glass slide and the proteins in the sample are captured on to the glass slide. Another antibody which binds to a different epitope of the protein is used to detect the protein. C) Bead-based array (Luminex platform). The Luminex bead is coated with the capture antibody which binds to the protein in the sample. Another antibody which binds to a different epitope is labeled with fluorescence for the detection. Red laser detects bead and green laser detects the antibody.