Chapter 4 Self-check questions

. Which of the following is not a mechanism for termination of tyrosine kinase activity of EGFR?

Additional phosphorylation.

Dephosphorylation of regulatory phosphorylated tyrosine residues.

Inhibition of receptor endocytosis and degradation.

Binding of negative regulators to the kinase domain

. Which one of the following is the molecular target of the therapeutic drug, Trastuzumab (Herceptin)?

The tyrosine kinase domain of ErbB2

The extracellular domain of ErbB2

The transmembrane domain of ErbB2

EGF

. Which one of the following statements is false?

MAPKK (MEK) is phosphorylated by activated Raf.

MAPKs function only in the cytoplasm

The MAP kinase family contain proteins that are serine/threonine kinases.

MAPKs affect the activity of transcription factors via phosphorylation.

. Which of the following therapeutic drugs target Raf tyrosine kinase activity?

Imatinib (Gleevec) and Dasatinib (Sprycel)

Trastuzumab (Herceptin) and Cetuximab (Erbitux)

Gefitinib (iressa)) and Afatinib (Giotrif)

Sorafenib (Nexavar) and Vemurafenib (Zelboraf)

. Which of the following statements is false, regarding the chronological sequence of events of the EGF signal transduction pathway?

…- SOS → RAS-GTP → RAS-GDP → RAF → MEK …

EGF → binding to EGFR → receptor dimerization → autophosphorylation …

Grb2 recognises the phosphate on EGFR with its SH2 domain and recruits the protein SOS via its SH3 domain.

The EGFR signal transduction pathway illustrates how growth factor signals from outside the cell are passed through the cell and get carried to the nucleus to affect gene expression.

. Which one of the following statements is false?

Patients with specific mutations in the EGFR gene respond to Geftinib (Iressa).

Patients with KRAS mutations respond to Cetuximab (Erbitux), a monoclonal antibody that targets EGFR.

The FDA now recommends screening for KRAS mutations before using Erbitux.

Herceptin is the first genomics-based therapy administered selectively based on the molecular profile of the tumour.

. Which one of the following statements is false?

Many growth factor receptors are tyrosine kinases.

SH2 is an example of a protein domain that has high affinity binding for phosphorylated EGFR.

Raf initiates a serine/threonine kinase cascade.

Raf is activated by the kinsae activity of RAS.

. Which one of the following statements is true?

Retroviruses are a major cause of human cancers.

Proto-oncogenes are altered forms of normal genes.

Oncogenic activation of receptor tyrosine kinases may occur through specific mutations that lead to constitutive tyrosine activation.

Oncogenic activation may not occur via epigenetic mechanisms.

. Which one of the following statements about pharmacogenomics is true?

It is the study of the influence of epigenetic modifications to drug metabolism.

It is the study of the influence of the genome on an individual's response to a drug.

It is the study of drugs that modify the genome.

It did not influence the patient response to Gefitinib (Iressa).

. Which of the following cancer drugs is not classified as a small molecule tyrosine kinase inhibitor?

Gilotrif (afatinib)

Gleevec (imatinib).

Erbitux (cetuximab)

Tarceva (erlotinib)

. In relation to interacting transcription factors, which one of the following statements is false?

Both Myc and MAX contain a basic helix-loop-helix leucine zipper.

Upon interaction with Myc, MAX down regulates tumor growth and suppresses oncogene regulation.

Upon interaction with MAD or Mxi-1, MAX antagonizes the function of myc.

The action of MAX is dependent on the identities of its partners.

. Which of the following statements are NOT a consequence of oncogenes being present on ecDNA?

They are highly expressed due to open chromatin conformation.

They are equally distributed upon cell division

Oncogene amplification occurs.

Proto-oncogene activation occurs.

. During the development of the drug gefitinib (Iressa), pharmacogenomics revealed that

Germline mutations affect the drug's pharmacokinetics

EGFR somatic mutations correlate with a negative clinical response.

Oncogene amplification occurs on ecDNAs and blocks a drug response.

EGFR somatic mutations correlate with a positive clinical response.

. Which of the following is evidence that EGFR is phosphorylated after EGF treatment?

Phosphorylation is directly visible under a light microscope.

Phosphorylation can be detected by next generation sequencing

Phosphorylation can be detected by a labelled antibody that detects phosphorylated EGFR via immunofluorescence microscopy.

Radiolabelled ATP can be used to detect phosphorylated EGFR in single cells via a scintillation counter.

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