Figure 6.

Entrance into mitosis is hastened by premature inactivation of p42 MAPK after parthenogenetic activation. A CSF-arrested extract was incubated with U0126 (100 μM) or an equal volume of DMSO (1%) for 40 min on ice. Calcium chloride (400 μM) was then added to each, and samples were removed for analysis. (A) Western blot analysis with the MAPK-specific antibody DC3. U0126 treatment (bottom) resulted in premature inactivation of p42 MAPK relative to that of the control extract (top). (B) Histone H1 kinase activities for control (□) and U0126-treated (▪) extracts. U0126 did not measurably alter the rapid inactivation of Cdc2 but did accelerate its reactivation. (C) NEBD in control and U0126-treated extracts.