Estrogen receptor (ER) is an important transcription factor, which is up-regulated in 70% of all breast cancers. Using the known ER motif to scan the genome yields many thousands matches, although not all of them are functional. Give the following three matches to the motifs, can you use comparative genomics approaches to judge which one is most likely functional (hint, check UCSC genome browser)?
Chromosome: Start-End (in human genome version Hg17 coordinates)
a. chr22:41,455,123-41,455,140
b. chr21:41,974,930-41,974,948
c. chr21:15,299,684-15,299,702
d. chr22:45,652,554-45,652,572