FAS and lymphoma: ATM deficiency results in the upregulation of the antiapoptotic protein FLIP (FLICE-like inhibitory protein) and confers resistance to programmed cell death elicited by Fas and TRAIL (tumor necrosis factor related apotosis inducing ligand) death receptors, suggesting a novel possible link between ATM loss of expression and the development of leukaemia and lymphomas [26,27].