Figure 8.

Elucidating the cause of the calcium wave in PC-3 cells. Left column, histogram, and scatter plots showing a calcium wave in cells seeded on a Mylar substrate. This result indicates that the wave is not caused by ultrasound reflection by the substrate. Center column, histogram, and scatter plots showing ultrasound responses of cells freshly seeded on a Cell-Tak-coated Petri dish. A calcium wave occurs even in the absence of gap junctions. Right column, baseline (top), and background-subtracted (bottom) fluorescence images of ultrasound responses occurring after scraping a channel of cells off the substrate. Red asterisks indicate the center position of the ultrasound focus. Calcium responses occurred on both sides of the gap, suggesting that calcium waves in invasive cancer cells are caused by release of signaling molecules that diffuse through the extracellular space. Scale bar is 500 µm.