Fig. 8. P2Y1R ectopically expressed in MDCK cells lacking this receptor. (A) Measures of intracellular calcium changes show that MDCK cells do not respond to P2Y1R agonists (n=6-8). ATP and UTP, but neither ADP nor 2-MeSADP, provoke rises in intracellular Ca2+ levels in MDCK cells, further indicating that these cells do not express P2Y1R. Data are means ± s.e.m. (B) MDCK cells permanently transfected to express the P2Y1R (MDCK/P2Y1R). Cells were selected for ectopic P2Y1R expression levels lower than those of the endogenous receptor of FRT cells.