Fig. 1.

mRNA expression of the P2 receptor genes using real-time quantitative RT-qPCR. The expression level of the receptors was normalized to their respective housekeeping genes. a The expression level of P2X₄R was arbitrarily expressed as 1. The gene expression levels of the other P2XRs were expressed as relative values to that of P2X₄R. b The expression level of P2Y₂R was arbitrarily expressed as 1. The gene expression levels of the other P2YRs were expressed as their relative values to that of P2Y₂R; n = 3 for each receptor and each AEC