# X and Y axis meanings

**URL:** <https://forum.depmap.org/t/x-and-y-axis-meanings/1109>\
**Category:** Q&A\
**Tags:** compound-screens\
**Created:** [January 4, 2022, 10:40pm UTC](https://forum.depmap.org/t/x-and-y-axis-meanings/1109 "2022-01-04T22:40:52Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![vaibhavj](https://avatars.discourse-cdn.com/v4/letter/v/bb73d2/32.png) [@vaibhavj](https://forum.depmap.org/u/vaibhavj)\
**Post date:** [January 4, 2022, 10:40pm UTC](https://forum.depmap.org/t/x-and-y-axis-meanings/1109/1 "2022-01-04T22:40:52Z")

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Dear DepMap members, I am interested in checking the drug sensitivity of melanoma lines to atorvastatin drug in relation to the LDLR protein levels. I created a graph but not sure what X and Y mean exactly. I am attaching a screen shot of the graph.  
Specific questions are

1. Do positive values on Y axis indicate the drug is more toxic to cancer cells? What is the definition of Drug sensitivity and what assay was used to determine it?
2. On X axis, what is the meaning of numbers from -2 to +1? Is this expression level arbitrary when cells were treated with this compound and vehicle control followed by mass spec? -2 means 2 fold reduction in the expression levels of LDLR?  
 ![LDLR](https://canada1.discourse-cdn.com/flex035/uploads/depmap/original/1X/781849c6ba7633ac9105ca561d85ac009d117f31.jpeg)

Thanks,  
VJ

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**Author:** ![jmmcfarl](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/jmmcfarl/32/16_2.png) [@jmmcfarl](https://forum.depmap.org/u/jmmcfarl)\
**Post date:** [January 5, 2022, 8:06pm UTC](https://forum.depmap.org/t/x-and-y-axis-meanings/1109/2 "2022-01-05T20:06:21Z")

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Hi VJ,

1. In this case the y-axis represents cell viability (log2 fold change of estimated cell abundance of drug-treated cells compared to controls). This is using the PRISM assay. You can refer to [this paper](https://www.nature.com/articles/s43018-019-0018-6) for more details.

2. The x-axis data in this case are taken from the proteomics data described in Nusinow et al, and represent relative protein abundance. For the precise interpretation of these values, please see [this guide](https://www.biorxiv.org/content/10.1101/2020.02.03.932384v1).

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**Author:** ![vaibhavj](https://avatars.discourse-cdn.com/v4/letter/v/bb73d2/32.png) [@vaibhavj](https://forum.depmap.org/u/vaibhavj)\
**Post date:** [January 6, 2022, 5:00pm UTC](https://forum.depmap.org/t/x-and-y-axis-meanings/1109/3 "2022-01-06T17:00:38Z")

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Hi James, thank you very much for the reply. I am still confused with this, please let me know if I am correct:  
A value on Y axis higher than 0 means cells are growing and hence less sensitive to be killed by a drug? Like in this graph higher expression of LDLR (let’s say LDLR, X axis value is 1.5 and Y axis value is -3) is making cells susceptible to be killed by atorvastatin?  
Best,  
VJ

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**Author:** ![jmmcfarl](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/jmmcfarl/32/16_2.png) [@jmmcfarl](https://forum.depmap.org/u/jmmcfarl)\
**Post date:** [January 7, 2022, 4:15pm UTC](https://forum.depmap.org/t/x-and-y-axis-meanings/1109/4 "2022-01-07T16:15:37Z")

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Hi VJ,

Larger magnitude values on the y-axis mean less sensitivity to the drug, yes. 0 represents no log-fold change viability measured relative to vehicle control.

This plot indicates that cell lines with higher LDLR protein levels tend to be more sensitive to the drug