Primary culture of embryonic heart from Rosa 26 mouse with Cre-dependent green downward DAG biosensor expression. Cells were treated with tamoxifen to induce Cre recombinase expression. Images collected with a 20X, 0.7 N.A. lens, on a confocal microscope imaging at 5 second intervals. This is raw data with no bleaching correction or background subtraction. The addition of Phorbol Ester produced a pronounced reduction in fluorescence. Better images should be possible with higher N.A. lenses and sensitive cameras.