Figure 8.

Mos-induced interphase arrest appears unrelated to the DNA replication checkpoint. (A) Upper, H1 kinase activity in extracts supplemented with buffer (□) or aphidicolin (0.4 mg/ml) and 2000 sperm/μl (▪). Lower, immunoblot of parallel samples probed with a MAP kinase-specific antibody (DC3). Note the absence of shifted MAP kinase in the aphidicolin-treated samples. (B) The presence of DNA is not required for the Mos-induced arrest. Cdc2 kinase activity in cycling extracts supplemented with buffer (□) or Mos (▪) and no added sperm chromatin.