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RB
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I. (noun)
Sense 1
Meaning:
A soft silvery metallic element of the alkali metal group; burns in air and reacts violently in water; occurs in carnallite and lepidolite and pollucite
Synonyms:
atomic number 37; Rb; rubidium
Classified under:
Hypernyms ("Rb" is a kind of...):
metal; metallic element (any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.)
Holonyms ("Rb" is a substance of...):
carnallite (a white or reddish mineral consisting of hydrous chlorides of potassium and magnesium; used as a fertilizer and as a source of potassium and magnesium)
lepidolite (a mineral of the mica group; an important source of lithium)
pollucite (a rare mineral that is an important source of cesium)
Context examples:
Two cell cycle kinases, CDK4/6-cyclin D and CDK2-cyclin E, and the transcription complex that includes Rb and E2F are pivotal in controlling this checkpoint.
(G1/S Checkpoint Pathway, NCI Thesaurus/BIOCARTA)
An adenovirus serotype 5 strain, selectively replication competent in cells defective in the Rb/p16 tumor suppressor pathway, with potential oncolytic activity.
(Oncolytic Ad5-Delta 24RGD, NCI Thesaurus)
Signaling from Ras to Raf to MEK to ERKs induces Cyclin D1 expression, allowing Cyclin D1 to complex with Cdk4 and Cdk6 and phosphorylate Rb.
(G1 to S Transition Pathway, NCI Thesaurus/BIOCARTA)
Association with the tumor suppressor Rb represses E2F-1 activity, and this repression is relieved when the cdk2/cyclin E complex at the G1 to S phase transition phosphorylates Rb.
(E2F1 Degradation Pathway, NCI Thesaurus/BIOCARTA)
Key among these are p53, the cdk inhibitors (p15, p16, p18, p19, p21, p27), and Rb, all of which act to keep the cell cycle from progressing until all repairs to damaged DNA have been completed.
(Cyclin Regulation of Cell Cycle Pathway, NCI Thesaurus/BIOCARTA)
During G1, cycD/CDK phosphorylation of Rb/HDAC repressor permits E2F/DP1 transcription of genes that promote the G1/S switch and DNA replication. p53 induces p21 inhibition of cycD/CDK; Mdm2 inhibits p53/p21.
(Negative Regulation of G1 Phase, NCI Thesaurus)
The serine/threonine kinase CDK4 is found in a complex with D-type G1 cyclins and is the first kinase to become activated upon mitogenic stimulation, releasing cells from a quiescent stage into the G1/S growth cycling stage; CDK-cyclin complexes have been shown to phosphorylate the retinoblastoma (Rb) transcription factor in early G1, displacing histone deacetylase (HDAC) and blocking transcriptional repression.
(CDK4 Inhibitor P1446A-05, NCI Thesaurus)
A type of atomic spectroscopy capable of qualitatively or quantitatively determining certain cations (particularly Na, K, Rb, Cs, Ca, Ba, Cu) by utilizing a low temperature flame capable of exciting a valence electron to an upper energy state which emits light at a wavelength unique to each cation as the electron returns to its ground state.
(Flame Photometry, NCI Thesaurus)
One of the key targets of activated cdk2 complexed with cyclin E is the tumor suppressor Rb.
(Cyclin E Degradation Pathway, NCI Thesaurus/BIOCARTA)
Inhibition of Rb phosphorylation prevents CDK-mediated G1-S phase transition, thereby arresting the cell cycle in the G1 phase, suppressing DNA synthesis and inhibiting cancer cell growth.
(CDK4/6 Dual Inhibitor LY2835219, NCI Thesaurus)
