Step 1: Two different types of antibodies are coated on the plate uniformly and standards and/or samples are added to the well.

Step 2: Targeted antibodies bind to the standards and/or samples.

Step 3: Antibodies labeled with different colored fluorescent probes are added to the well.

Step 4: Antibodies with different colored fluorescent probes binds to their targeted proteins and the specific fluorescent signals are read by fluorescent plate reader.

Step 1: Two different types of antibodies are coated on the plate uniformly. Standards and/or samples along with two different fluorescent labeled protein are added to the well.

Step 2: Fluorescent labeled protein compete with none labeled protein binding to the antibody. The blank has the highest fluorescent signal and the signal decreases when the non-labeled protein concentration increases.

Step 1: Two different types of antibodies are coated on the plate uniformly. Standard and/or sample along with fluorescent labeled protein are added to the well.

Step 2: Fluorescent labeled protein compete with none labeled protein binding to the antibody. The blank has the highest fluorescent signal and the signal decreases when the non-labeled protein concentration increases. The second targeted antibody binds to the standard and/or sample.

Step 3: The second fluorescent labeled antibody is added to the well.

Step 4: The fluorescent labeled antibody binds to their targeted protein and the specific fluorescent signal is read by fluorescent plate reader.