FAS and neoplasm: Tumour cells may obtain the ability to evade immune surveillance by several strategies, including a lack of adequate T-cell costimulation (Melero et al, 1997; Thomas et al, 1999), downregulation of cell-surface MHC class I expression (Goodenow et al, 1985; Restifo et al, 1993; Imboden et al, 2001), dysfunction of Fas (CD95/APO1)-mediated apoptosis (Hahne et al, 1996; Strand et al, 1996) and secretion of immunosuppressive factors, such as transforming growth factor-β (Inge et al, 1992) or interleukin-10 (Fiorentino et al, 1991a, 1991b).