P2Y receptor mRNA expression in MLO-Y4. Agarose gel electrophoresis visualizing RT-PCR amplified P2 receptor cDNA from reverse-transcribed MLO-Y4-derived RNA. The gel demonstrates the expression of P2Y2, P2Y4, P2Y12 and P2Y13 receptor mRNA in MLO-Y4 osteocytes. P2Y1 receptor mRNA could not be identified. DNA marker, 100 bp DNA ladder. Positive control (+), cDNA obtained from BALB mouse bone marrow, brain and spleen. Negative control (−), sterile water. bp base pairs