In the case of gammaherpesviruses, human herpesvirus 8 (HHV8) or Kaposi’s sarcoma associated herpesvirus (KSHV) studies have shown that primary effusion lymphoma (PEL) cells are immunophenotypically similar to pre-plasma cells and have unspliced XBP-1 mRNA [72, 73]. Here, XBP1 is linked to primary effusion lymphoma.