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Western blot analysis of extracts from 293 cells, transfected with control (-) or SignalSilence® Rb siRNA I (+), using Rb (4H1) Mouse mAb #9309 and p44/42 MAPK (Erk1/2) (3A7) Mouse mAb #9107. The Rb antibody confirms silencing of Rb expression, while the p42 MAPK antibody is used to control for loading and specificity of Rb siRNA.

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Fluorescent detection of SignalSilence® Control siRNA (Fluorescein Conjugate) #6201 in living HeLa cells 24 hours post-transfection, demonstrating nearly 100% transfection efficiency.

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Product Usage Information

CST recommends transfection with 50-100 nM Rb siRNA I 48 hours prior to cell lysis. For transfection procedure, follow protocol provided by the transfection reagent manufacturer. Please feel free to contact CST with any questions on use.


Storage: SignalSilence® siRNA is supplied in RNAse-free water. Aliquot and store at -20ºC.

Product Description

SignalSilence® Rb siRNA I from Cell Signaling Technology (CST) allows the researcher to specifically inhibit Rb expression using RNA interference, a method whereby gene expression can be selectively silenced through the delivery of double stranded RNA molecules into the cell. All SignalSilence® siRNA products from CST are rigorously tested in-house and have been shown to reduce target protein expression by western analysis.


The retinoblastoma tumor suppressor protein Rb regulates cell proliferation by controlling progression through the restriction point within the G1-phase of the cell cycle (1). Rb has three functionally distinct binding domains and interacts with critical regulatory proteins including the E2F family of transcription factors, c-Abl tyrosine kinase, and proteins with a conserved LXCXE motif (2-4). Cell cycle-dependent phosphorylation by a CDK inhibits Rb target binding and allows cell cycle progression (5). Rb inactivation and subsequent cell cycle progression likely requires an initial phosphorylation by cyclin D-CDK4/6 followed by cyclin E-CDK2 phosphorylation (6). Specificity of different CDK/cyclin complexes has been observed in vitro (6-8) and cyclin D1 is required for Ser780 phosphorylation in vivo (9).


RNA interference has been used to silence Rb protein expression in prostate cancer cells resulting in increased Bcl-2 protein levels (10).


1.  Sherr, C.J. (1996) Science 274, 1672-7.

2.  Nevins, J.R. (1992) Science 258, 424-9.

3.  Welch, P.J. and Wang, J.Y. (1993) Cell 75, 779-90.

4.  Hu, Q.J. et al. (1990) EMBO J 9, 1147-55.

5.  Knudsen, E.S. and Wang, J.Y. (1997) Mol Cell Biol 17, 5771-83.

6.  Lundberg, A.S. and Weinberg, R.A. (1998) Mol Cell Biol 18, 753-61.

7.  Connell-Crowley, L. et al. (1997) Mol Biol Cell 8, 287-301.

8.  Kitagawa, M. et al. (1996) EMBO J 15, 7060-9.

9.  Geng, Y. et al. (2001) Proc Natl Acad Sci USA 98, 194-9.

10.  Huang H et al. (2004) Oncogene 23, 2161–76


Entrez-Gene Id 5925
Swiss-Prot Acc. P06400


For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology® is a trademark of Cell Signaling Technology, Inc.
SignalSilence® is a trademark of Cell Signaling Technology, Inc.
Limited Use Label License, RNA interference: This product is licensed under European Patent 1144623 and foreign equivalents from Ribopharma AG, Kulmbach, Germany and is provided only for use in non-commercial research specifically excluding use (a) in drug discovery or drug development, including target identification or target validation, by or on behalf of a commercial entity, (b) for contract research or commercial screening services, (c) for the production or manufacture of siRNA-related products for sale, or (d) for the generation of commercial databases for sale to Third Parties. Information about licenses for these and other commercial uses is available from Ribopharma AG, Fritz-Hornschuch-Str. 9, D-95326 Kulmbach, Germany.