1. Antibodies produced against a phospho-peptide contain three species: phospho-specific, dephospho-specific, and pan-specific.

2. To purify the phospho-specific antibody, two affinity steps are needed.

3. The first step may be the posphopeptide affinity column. Bound antibodies are eluted. The dephospho-specific antibodies will not bind.

4. The second step may be the dephospho-specific affinity column. Flow through is collected. The pan-specific antibodies will bind on the affinity column.