You don't want to know. Promoter sequences, of course, in the human genome.
They aren't difficult as much as they are frustrating. If you don't time your collection times perfectly, they mate without your knowledge and contaminate your results. Much like human beings.
If you ever manage to find yours, I would like to read them. It's always important to review what your peers publish - I've found myself learning tremendously this way.
[[ He includes three links to three separate articles: "The effects of promoter activity on the allelic expression of Drosophila melanogaster mutants." Published in 2003 by Harold Shekh, Jasper Archer, and Arthur Kemp in Molecular and Cellular Biology
"The role of cAMP in lipid metabolism." Published in 2005 by Caroline Scott and Jasper Archer in Molecular and Cellular Biology
"A detailed examination of four promoter regions found on human Chromosome 15." Published in 2008 by Jasper Archer in Molecular and Cellular Biology ]]