Anti-MDM2 (phospho S166) Antibody

Research on p53 pathway signaling depends on reagents that distinguish the inactive form of MDM2 from its signaling-competent, kinase-activated state. This unconjugated rabbit polyclonal IgG from Antibodies.com was raised against a synthetic phosphopeptide corresponding to the region of human MDM2 that contains serine 166, the AKT/PKB site whose modification drives MDM2 nuclear import and amplifies its E3 ubiquitin ligase activity toward p53. Affinity purification against the phosphopeptide, combined with depletion of non-phospho-specific antibodies on the unmodified peptide, restricts detection to MDM2 carrying the phosphate on S166.

The reagent is supplied as 100 µl of liquid in a PBS-based buffer with 50% glycerol and 0.02% sodium azide, and is validated for Western blot and immunofluorescence on human, mouse, and rat samples. In Western blot, the antibody resolves a band at approximately 90 kDa, with an additional ~55 kDa species frequently observed, in lysates from cells exhibiting active AKT signaling. In immunofluorescence, it highlights the cytoplasmic-to-nuclear shift of MDM2 that follows growth factor stimulation, genotoxic stress, or oncogenic transformation, making the antibody well suited to time-course and dose-response studies of upstream kinase activity. Because phosphorylation at S166 is a transient regulatory mark, careful timing of sample collection is important. The polyclonal format also gives broader recognition of neighbouring epitopes, which improves detection when adjacent residues carry additional post-translational modifications. Aliquot the stock upon first use, store at -20 °C to limit freeze-thaw cycles, and protect from light to preserve antibody integrity across repeated experiments.