The retinoblastoma protein (Rb, pRb, and Rb1) is a tumor suppressor protein (and a member of the pocket protein family) that functions by inhibiting progression from G1 to S phase of the cell cycle. Rb is also involved in terminal differentiation and apoptosis. Rb binds and inhibits transcriptional activity of members of the E2F family of transcription factors. When Rb is phosphorylated by members of the Cyclin Dependent Kinase family (CDKs), it loses its affinity for the E2F transcription factors, transcriptional repression is relieved, and the cells proceed through the G1 to S phase transition and go on with the cell cycle. Activation of the Cyclin D-dependent kinases can be prevented by Inhibitor of Kinase 4 (INK4), as well as by other mechanisms. Overexpression of INK4 inhibits phosphorylation of Rb by CDKs, and thus prevents cell cycle progression. Loss of transcriptional repression by Rb is involved in many different types of cancer. Study of the retinoblastoma protein and inactivation of Rb by phosphorylation at multiple different residues has been the subject of intense study due to the fundamental role of Rb in many normal and disease based physiological processes.


Rb Singleplex Products

Our Rb immunoassays provide fast, accurate, reproducible, and highly sensitive measurements of Rb. MSD’s MULTI-ARRAY technology uses simple protocols, requires minimal sample, and quantifies analyte concentration over a wide dynamic range.


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Rb Multiplex Products

Our multiplex panels let you process up to 10 analytes simultaneously in each well of a MULTI-SPOT microplate. They provide the same outstanding performance as our singleplex immmunoassays while saving money, sample, and time.


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Related Custom Assays

The following related assays are not in our catalog but may be available as custom orders. Custom orders are typically shipped in 3 to 6 weeks. You may request pricing and availability for the assays below using our Custom Assay Quote Request form.

  • Phospho-Rb -
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