Scent marks
Scent marks are what animals leave when they are marking their territory. The leader of the pack rubs his/her scent on his/her pack. This helps establish which animal belongs to which pack, and also which animal is the leader.
Scent Marks Media
Image of ENCODE data in the UCSC Genome Browser. This shows several tracks containing information on gene regulation. The gene on the left (ATP2B4) is transcribed in a wide variety of cells, (see also the H3K4me1-data.) The gene on the right is only transcribed in a few types of cells, including embryonic stem cells.
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Media related to Scent marking at Wikimedia Commons