To understand the influence of MLH1 status on CR and long-term survival of advanced EOC patients, we have investigated the apoptotic signalling pathways engaged in p53-deficient ovarian cancer cells in response to chemotherapeutic agents, cisplatin and 6-TG, and have identified a novel link between the expression of the mismatch repair protein MLH1 and the stability of XIAP, an anti-apoptotic protein and caspase inhibitor. The gene discussed is XIAP; the disease is ovarian cancer.