“…While antiproliferative effects of metabotropic P2Y-receptors have been documented in various tumour models (Fang et al, 1992;Vandewalle et al, 1994;Höpfner et al, 1998;Katzur et al, 1999;Schultze-Mosgau et al, 2000), apoptosis inducing effects of P2Y-receptors have only been shown in MCF-7-breast cancer (Vandewalle et al, 1994) and colorectal carcinoma cells However, the main P2-receptor subtypes implicated in apoptosis are ionotropic P2X-receptors of the subtypes P2X 1 and P2X 7 (Chvatchko et al, 1996;Di Virgilio et al, 1998;Ferrari et al, 1999). P2X-receptors are mainly found in excitable tissues such as smooth muscles and nerves, although P2X 4 -receptors have also been reported in endocrine tissues (Ralevic and Burnstock, 1998).…”