Fig. 7. Progesterone does not alter Xenopus oocyte serine/threonine phosphatase activities. Phosphatase activities were determined in the absence or presence of 100 nM okadaic acid. Means±s.e. of three (with okadaic acid) and five (without okadaic acid) independent experiments are shown. At least 50% of the oocytes at 180 minutes had undergone GVBD. The basal phosphatase activities in G2 oocytes were 76±6.5 nmol phosphate released per oocyte in 30 minutes.