P2RX4 and ocular melanoma: Real-time quantitative PCR showed that P2X4 expression at the mRNA level in the OM group was significantly higher than that in the control group (p < 0.01), whereas after treatment with P2X4 shRNA or imperatorin, the P2X4 expression level was significantly lower compared to the OM group (p < 0.01) (Figure 6a).