P2RX7 and Familial prostate cancer: As extracellular ATP was previously shown to be an inducer of cell death in prostate cancer (Shabbir et al, 2008), we hypothesised that the effects of alkaline phosphatase knockdown in prostate cancer cells may be mediated by the increased levels of extracellular ATP, with differing concentrations of extracellular ATP well known to activate distinct purinergic receptors such as the P2X7 receptor.