Searching for regulatory elements

From a list of differential genes. 

## 6.1 Extracting the coordinates of genes
Using `biomartr`

## 6.2 Adding or substracting X nts
For instance, 5000 nts 
If gene is on DNA strand + then substract 5000 nts  
If gene is on DNA strand - then add 5000 nts

Promoter retrieval using GenomicRanges
MEME for motif...
