The role of P2Y2 in mediating the effects of ATP on NPC cells. A: Schematic representation of the constructed vectors. CMV, CMV promoter; EGFP, enhanced green fluorescent protein gene; U6, U6 promoter. B: P2Y2 and OPN regulate the growth inhibitory effects of ATP on NPC cells. The levels of P2Y2 and OPN were significantly decreased after transfection with the shRNA expressing vector or siRNA. P2Y2 overexpression enhanced the growth inhibitory effect of ATP on NPC cells, whereas OPN overexpression reversed this effect. There were statistically significant differences between the control and treated conditions: *P < 0.05. C: The role of P2Y2 expression in the effects of ATP on the cell cycle and apoptosis of CNE-2 cells. P2Y2 expression increased the percentage of G1-phase cells and decreased the proportion of G2/M-phase cells. The overexpression of P2Y2 increased the level of apoptotic cells in ATP treated cells.