Carinogenesis

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Carinogenesis

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Tiff
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05/15/08 - 10:49 AM

The major mechanism by which repeated application of croton oil (phorbol ester), after a single application of a mutagenic agent on the skin, promotes carcinogenesis is:

A. Induction of chromosome breaks
B. Inhibition of DNA repair
C. Activation of protein kinase C
D. Activation of endogenous viruses
E. Amplification of growth factor receptor genes

new_n_lost
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05/15/08 - 01:29 PM

No freaking clue

Shot in the dark >> C. Activation of protein kinase C

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jean robert
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05/15/08 - 05:36 PM

B

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sigh
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05/15/08 - 07:15 PM

GoodGirl
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05/15/08 - 08:42 PM

C, activates protein Kinase C --> (+) cell divisions.

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Tiff
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05/16/08 - 08:48 AM

sigh wrote:
C.

C is correct. Phorbol esters cause tumor promotion by activating protein kinase C. This enzyme phohorylates several substrates in signal transduction pathways, including those activated by growth factors, and the cells divide. Forced cell division presiposes the accumulation of mutations in cells previously damaged by exposure to a mutagenic agent.

new_n_lost
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05/16/08 - 01:23 PM

new_n_lost wrote:
No freaking clue

Shot in the dark >> C. Activation of protein kinase C

Me Shot in the Dark works

Me happy. sticking out tongue

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Tiff
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05/16/08 - 02:14 PM

Haha. Maybe I should apply that old test taking policy of when in doubt choose C. grin

spinal shock
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05/17/08 - 11:35 AM

looks like xero derma pegmentosum, so C

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spinal shock
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05/17/08 - 11:38 AM

#10

sorry i mean B

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Tiff
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05/17/08 - 05:37 PM

#11

spinal shock wrote:
looks like xero derma pegmentosum, so C

Thought about that mechanism myself, but it can't be because xeroderma pigmentosa is due to UV light. This case is due to some sort of carcinogen making the answer C - protein kinase. What I still don't get is why protein kinase C? Based on the explanation I provided above the carcinogen phophorylates substrates activated by growth factors. Aren't growth factors mediated via a tyrosine kinase mechanism?

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