The Phospho-Rb (Ser780) antibody is a tool used to detect the retinoblastoma protein (Rb) when phosphorylated at serine residue 780. a key post-translational modification involved in cell cycle regulation. Rb, a tumor suppressor encoded by the *RB1* gene, plays a critical role in controlling the G1-to-S phase transition by binding and inhibiting E2F transcription factors. Phosphorylation of Rb by cyclin-dependent kinases (CDKs), particularly CDK4/6-cyclin D complexes, at specific residues (including Ser780) disrupts its interaction with E2F, allowing cell cycle progression.
The Ser780 phosphorylation site is a well-characterized marker of CDK4/6 activity and is commonly used to assess Rb inactivation in cancer and cell proliferation studies. Dysregulation of Rb phosphorylation is implicated in tumorigenesis, as hyperphosphorylation (and subsequent functional loss of Rb) is observed in many cancers. This antibody is widely employed in techniques like Western blotting, immunohistochemistry, and flow cytometry to study cell cycle dynamics, drug responses (e.g., CDK4/6 inhibitors), and disease mechanisms.
Its specificity for the phosphorylated form of Rb makes it valuable in distinguishing active versus inactive Rb states, aiding research on therapeutic targeting, cell differentiation, and apoptosis. Validation typically includes testing in models with Rb phosphorylation modulation (e.g., CDK4/6 inhibition) to confirm signal specificity.