I have got the IC50 data for a drug on different cell lines. How to define if the cell line is sensitive or resistant towards this drug?

Could anyone tell me how to define this?

  • 2
    $\begingroup$ A low IC50 marks a sensitive cell line, a high a resistant. $\endgroup$
    – Chris
    Commented Apr 9, 2015 at 8:28

1 Answer 1


From this post.

The IC50 is the concentration of inhibitor required to reduce the activity of a molecule/protein by one-half. It is the inverse of EC50. Usually inhibition curves looks sigmoidal so the IC50 is the middle point of the S curve. Here an example. (Note that the Y-axis can be pretty much anything, like enzyme activity and the X-axis is the concentration in a logarithmic scale).


Now for your actual question. The IC50 you got is by plotting a measure of the cell death rate vs the concentration of the drug. IC50 is expressed as a concentration so the higher the concentration of drug needed to kill the cell line the more resistant that cell line is. If the IC50 is very low then the concentration (or amount) of drug needed to kill the cell line is also very low which means the cell line is more sensitive.


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