There are a number of ways in which COX-2 may promote cancer progression, either through an effect on cancer cells, the associated immune response or angiogenesis in response to the tumour. There is evidence that COX-2 expression protects cells from apoptosis and conversely that treatment of CRC cells with selective COX-2 inhibitors causes cell-cycle arrest, growth inhibition and induction of apoptosis (Richter et al, 2001; Sheng et al, 1997 Sheng et al, , 1998 . Evidence from both animal models (Hansen-Petrik et al, 2002) and human studies (Sinicrope et al, 2004) suggests that modulation of cell survival by altered susceptibility to apoptosis is equally important in vivo.