Naked mRNA is not readily taken up by cells, but needs to be encased inside a protective envelope to gain entry.

In this sentence, I'm confused by the phrase taken up. After searching a dictionary, I'm even more bemused. I just couldn't find a meaning that matches this sentence appropriately. But I do have a hypothesis that according to one of the items of the meaning of "take up" in the dictionary, which is to begin a friendly or romantic relationship with (someone), I guess that maybe taken up is used as a figurative way to suggest that cells and mRNA can't coordinate well enough to function normally. If I'm wrong, please correct me.

By the way, I noticed that but is used in this sentence for conveying logical meaning. But it's more logical for me to use so. Can anyone explain why but is used as such?

  • 2
    It means that the cells don't absorb, or take in, the RNA easily. I couldn't find a dictionary definition for this sense, but I'm certain that's what it means. Commented Mar 4, 2022 at 9:13
  • OED defn 13d To use up (esp. a commodity or resource); to consume. Commented Mar 4, 2022 at 13:53

2 Answers 2


I found a dictionary definition for the phrasal verb "to take up" in the Oxford English Dictionary which seems relevant here. It has many definitions, and you have to scroll way down a huge page to find it. I have also included a recent citation.

To take up


a. transitive. Of a substance or body: to absorb (a fluid, moisture, etc.); to interact with and retain (a gas or other substance); to dissolve (a solid).

2011 I. Fraser & P. Marsack Bush Capital Year 133 The fungus too takes up food via its network of mycelial threads.

Source: oed.com

  • Well done. I don't have access to the OED. Commented Mar 4, 2022 at 14:14
  • @KateBunting - yeah it requires a login unfortunately. If you are in the UK, sometimes public libraries allow you to access it for free.
    – Billy Kerr
    Commented Mar 4, 2022 at 17:15

The sentence above could be rephrased as two separate sentences:

Naked mRNA is not readily taken up by cells.

Naked mRNA needs to be encased inside a protective envelope to gain entry.

Here, to “gain entry” appears to be synonymous to being “taken up,” as the sentence’s structure suggests.

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