4 A) Which of the following is NOT a common form of downregulation of cytokine a

ID: 262743 • Letter: 4

Question

4 A) Which of the following is NOT a common form of downregulation of cytokine and/or RTK signaling?

peroxisomal degradation of the receptor

ubiquitination and proteasomal degradation of the receptor and kinase

phosphotyrosine phosphatases

endocytosis of the receptor

4 B) Which of the following mutations would NOT result in constitutive activation of the associated signaling protein?

a mutation in NF?B that prevents association with its inhibitor

a mutation in Smad3 that mimics serine phosphorylation (S>D)

a mutation in Ras that prevents its hydrolysis of bound GTP to GDP

a mutation in MAP kinase that prevents its association with MAPKK

4A. Option A is correct.

Cytokine/RTK receptors are not generally degraded in the peroxisome.

4B. Option A is correct.

MAPK associating with MAPKK is required for its constitutive activation.

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