[BioC] functional clustering question

[Phguardiol at aol.com]

Hi,
I wonder if any packages could do the following:
First I m using human U133A affy chips on human cells. 
I have identified a set of genes differentially expressed between 2 groups and I d like to know if some of these share some common regulatory domains in their upstream regions like p53 specific sequence etc... which could help me to cluster these in a more functional way...
Any help is welcome
Thanks
Philippe