Arf is a tumor suppressor a. it blocks e2f dependent transcription of genes required to enter s phase. b. it sequesters mdm2 and prevents mdm2 mediated degradation of p53. c. it degrades dna during apoptosis. d. it acts a transcriptional co-activator and p53 transactivate its target genes. e. it p53 permeabilize the mitochondrial membrane and promote cytochrome c release.

Arf is a tumor suppressor because: b. It sequesters mdm2 and prevents mdm2 mediated degradation of p53.

Explanation:

Arf is a protein which is called tumor suppressor because it is responsible for preventing the growth of tumors. Arf inhibits the activity of mdm2.

Contrary to the Arf protein, which functions as a tumor growth suppressant, mdm2 is an oncogene, that is it's function is the increase of tumoral cells by genetic mechanisms that are already established.

In this equation also comes into play a protein called p53 which is nicknamed as "the genome guardian". P53 is also a part of the group of tumor suppressor.

One mechanism by which mdm2 can induce tumor activation and tumor growth is by inhibiting p53 by a mechanism called ubiquitination.

This point is where Arf acts. What Arf does is to inhibits that mechanism of ubiquitination of mdm2 on p53, leading to the inactivation of mdm2 and the stabilization of p53 so that this tumor suppressor can carry out it's physiological functions.

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Explanation:

Ya