Modulation of Ca2 signaling in starfish oocytes by the cortical actin cytoskeleton was also demonstrated in other ways. The treatment of oocytes with JAS, a well-characterized reagent that produces similar hyper-polymerization of cortical actin, also inhibited the 1-MA-induced Ca2 signals in a dose-dependent manner(Fig. 5b). The results of LAT A experiments further support the idea that the perturbation of actin polymerization or depolymerization can drasti cally impair 1-MA-triggered ca2 signaling. The cortical actin network must therefore play an important role in regulating Ca2+. release in maturing oocytes.