I want to calculate IC50 for MTT data by graghpad. I have two type of MTT data. First, 28 data point and second, 18 data point. In order to analyze in graghpad, I select analyze → XY analyses → nonlinear regression → dose response inhibition → ?
for this case, there are 4 functions: log(inhibitor) vs. response, log(inhibitor) vs. response-variable slope, log(inhibitor) vs. normalized response, log(inhibitor) vs. normalized response-variable slope.
What function must I select?
Dear as jebeli,
You should select the second one, log(inhibitor) vs. response-variable slope.
but before you begin analyzing, you should transform X data to Log X.
I totally agree. You should use the method having variable slope. Otherwise, the data fit is set to slope = 1 as an artificial restraint. The slope is a very helpful entitiy for assessing the data quality. As a reference, I highly recommend the following paper: B. Shoichet, J. Med. Chem. 2006, 49, 7274-7277. This paper mainly focuses on enzyme assays, but the explanations for phenomena such as steep slopes are also applicable to your MTT assay.
- Badges
- Science topic
- Similar topics
- Chemistry
- Pharmacology