Fig. 1.

Scratching monolayers stimulates cAMP synthesis in MDCK cells. Confluent monolayers of MDCK cells were maintained in 1.8 mM Ca²⁺ Ringer's solution containing 100 µM IBMX, a phosphodiesterase inhibitor. Cells were then wounded by scratching monolayers with a 27G needle 20 times, or treated with 100 µM ATP or 100 µM forskolin. The amount of cAMP was quantified by immunoassay and normalized to the amount of total protein. The number of experiments is indicated in parentheses. *P=0.0006.