Figure 4.

Internalization of P2Y₁ receptors in Madin-Darby canine kidney (MDCK) cells is independent of protein kinase C (PKC). MDCK cells stably expressing recombinant P2Y₁ receptors were preincubated for 10 min with the PKC inhibitors GF109203X (1 µM), Gö6983 (10 µM), Ro31-8245 (10 µM) or rottlerin (10 µM), following which either buffer or 100 µM ADP was added and the cells were further incubated for 30 min. MRS2500-binding sites were then quantified. All values are normalized to the total amount of radiolabelled MRS2500 binding in the absence of agonist treatment. Data shown are means of triplicate samples ± SEM from a representative experiment (n= 3). (B) The capacity of the PKC inhibitors to block phorbol 12-myristate 13-acetate (PMA)-promoted ERK phosphorylation in MDCK cells is shown. The inhibitors were used at the same concentrations as in (A). Per cent inhibition of PMA-promoted ERK phosphorylation is shown for each inhibitor (n= 3).