P2RX2 and Duchenne muscular dystrophy: In addition, P2X2, P2X5, and P2Y1 were found strongly expressed in the adult mdx mouse model (as a surrogate for Duchenne muscular dystrophy (DMD) research) muscle; the P2X5 and P2Y1 receptors were expressed first on activated satellite cells, P2Y1R also on a range of immune cells.