In the late ‘80s, the independent discovery of two monoclonal antibodies, α-APO-1 and α-Fas [5,6], able to trigger apoptosis and induce tumor regression, fostered major interest in the identification of TNF-related family members [7,8], including receptor Fas/CD95, to which α-APO-1 and α-Fas bind specifically. Here, FAS is linked to neoplasm.