Although the question of “which gene is involved?” is still very pertinent in research today, often equally important is “how is that gene regulated?”. Accordingly, one must turn one’s eyes from the protein-coding region of the DNA and instead look upstream at the promoter (and even more distal sequences). Within such sequences one will find—if the right tools are at hand—transcription factor binding site, thereby providing clues as to the gene’s regulation. cREMaG (cis Regulatory Elements in Mammalian Genome) is one such tool to help you acquire that information. This database contains information regarding the over-representation of transcription factor binding sites for a number of user-specified, co-expressed genes. (The logic here is that genes that are co-expressed are likely to be co-regulated.) The page is very simple and easy to use, with a straightforward and uncluttered layout. Users can search by one of five species: human, mouse, rat, dog, and cow.