In this case = ?

This case = "but it is not usually found in B-cells"?

Context:

They found that the lymphoma cells' growth was dependent on a receptor that normally regulates the growth of other immune cells, but it is not usually found in B-cells. However in this case, the Hodgkin-/Reed Sternberg cells 'hijacked' this receptor for their own purposes by activating some of the 'junk DNA'. In fact the lymphoma cells activated hundreds, if not thousands, of LTRs all over the genome, not just one.

More click:

http://www.sciencedaily.com/releases/2010/05/100502173845.htm