NS FL 3 B/B #8

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NS FL 3 B/B #8

Post by Sinc135 » Sun Nov 15, 2020 6:24 pm

Can anyone explain in further detail why C is wrong? I know that if you increase p53 this will lead to an increase in PTEN. Which will further inhibit the HER2 signaling pathway. But how does the inhibition via PTEN first occur in the esophagus at 16 weeks? It looks like inhibition via PTEN occurs in the esophagus at 14 weeks.

Appreciate your help.
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Joined: Wed May 27, 2020 7:25 pm

Re: NS FL 3 B/B #8

Post by NS_Tutor_Nancy » Mon Nov 30, 2020 2:21 pm


This kind of question can certainly pose a challenge because there is a lot of data to dissect here. It is important to note that the question stem specifically refers to what figure 2 tells you, so you need to be careful not to pull information from other parts of the passage. While it is true that signaling through the HER2 receptor is inhibited by the expression of p53, this is discussed in the first paragraph and shown visually in figure 1. If you just look at figure 2, you would not be able to make this conclusion. That is the first clue that choice C is not what you are looking for. For the second part of choice C, you want to figure out when the HER2 receptor first starts getting inhibited through the p53 pathway. You know that p53 activates PTEN which is what directly inhibits the HER2 path, so in figure 2 you want to find when PTEN first becomes present (indicated by +). Looking at figure 2, PTEN is - in the esophagus, stomach, and small intestine for weeks 12 and 14. In week 16, PTEN is + only in the esophagus, so this is where signaling is first inhibited.

I hope this helps!
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