P2RY4 and neoplasm: In this study, the significant over expression of uracil in tumor tissues (Fig. 1A) correlated with the gene expression of P2Y-receptors with an affinity with uracil precursor molecules (UTP, UDP, UDP-glucose), including P2RY2, P2RY4, P2RY6, and P2RY14. Specifically, we detected upregulated (12-fold) expression of the UDP-specific P2RY6 gene in tumor samples compared with normal samples (Fig. 3I).