Identification of P2X receptor transcripts in Huh-7 cell line. Human liver cells (Huh-7 cell) express multiple P2X receptor isoform transcripts. Representative products of the appropriate size were detected for receptors P2X2, P2X3, P2X5, P2X6 and P2X4. P2X1 and P2X7 were not detected over a broad range of conditions. PCR amplifications for all detected isoforms were repeated using 10 separate preparations of synthesized cDNA, from 10 separate experiments. All these identified isoforms were always present (10/10).