Both starfish eggs were injected with Ca Green dextran and imaged by confocal microscopy. The right egg was injected with a GST fusion protein composed of the two SH2 domains of phospholipase C gamma (132 micrograms/ml final concentration), and the left egg is control, and was injected with GST alone (190 micrograms/ml). Both eggs have a Ca action potential at fertilization. The control egg has a normal Ca wave, but the Ca wave in the right egg is much delayed. This is evidence that initiation of the Ca wave at fertilization involves activation of phospholipase C gamma, which then generates IP3. (Frames in the movie were obtained at 2 sec intervals).