# Expression log2(TPM+1)

**URL:** <https://forum.depmap.org/t/expression-log2-tpm-1/946>\
**Category:** Q&A\
**Created:** [October 8, 2021, 7:49pm UTC](https://forum.depmap.org/t/expression-log2-tpm-1/946 "2021-10-08T19:49:02Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Towhidul\_MM\_Islam](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/towhidul_mm_islam/32/322_2.png) [@Towhidul\_MM\_Islam](https://forum.depmap.org/u/Towhidul_MM_Islam)\
**Post date:** [October 8, 2021, 7:49pm UTC](https://forum.depmap.org/t/expression-log2-tpm-1/946/1 "2021-10-08T19:49:02Z")

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When the expression data was presented, it sometimes mentioned 0 or NAN. What is the difference? Does NAN mean the data is not available for the gene? Or not detectable (Not a number)?

Thanks in advance,

 ![Screenshot 2021-10-08 at 15.48.09](https://canada1.discourse-cdn.com/flex035/uploads/depmap/original/1X/6c0dfc926e31b0435403a648fd904da9ae1dda03.png)  
 ![Screenshot 2021-10-08 at 15.45.25](https://canada1.discourse-cdn.com/flex035/uploads/depmap/original/1X/316f1ac9b388019e001ba0768abc69db1bd88b7e.png)

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**Author:** ![jnoorbak](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/jnoorbak/32/12_2.png) [@jnoorbak](https://forum.depmap.org/u/jnoorbak)\
**Post date:** [October 12, 2021, 1:57pm UTC](https://forum.depmap.org/t/expression-log2-tpm-1/946/2 "2021-10-12T13:57:23Z")

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Hi, the cases with NAN are for cell lines for which we currently don’t have any expression data. Zero values are cases where the expression is actually zero.  
-best  
Javad

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**Author:** ![Towhidul\_MM\_Islam](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.depmap.org/towhidul_mm_islam/32/322_2.png) [@Towhidul\_MM\_Islam](https://forum.depmap.org/u/Towhidul_MM_Islam)\
**Post date:** [October 12, 2021, 2:11pm UTC](https://forum.depmap.org/t/expression-log2-tpm-1/946/3 "2021-10-12T14:11:49Z")

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Hi Javad,  
Many many thanks for your reply and email.  
regards,