Fig. 4. Requirement of FoxM1-dependent G2-M progression for neuronal differentiation. (A) Xenopus embryos were analyzed for Cdc25B and cyclin B3 by RT-PCR. (B) Embryos pre-injected with control MO or Cdc25B-MO (18 ng) at the one-cell stage were cultured until st. 32 and photographed to show morphological phenotypes. (C) Embryos pre-injected with both lacZ mRNA (100 pg) and control MO or Cdc25B-MO (18 ng) at one blastomere at the two-cell stage were fixed at st. 13, immunostained for pH3, and analyzed as in Fig. 1B. ^*P<0.01. (D) Embryos were co-injected with lacZ mRNA (100 pg) and either control MO or Cdc25B-MO (18 ng) at one blastomere at the two-cell stage, cultured until st. 14, and analyzed by WISH. In each panel, the injected side (β-Gal, red) of the embryo is on the right (dorsal view, anterior up). (E) Animal caps from the late blastula embryos pre-injected with control MO or Cdc25B-MO (36 ng) at the one-cell stage were cultured with or without Activin (200 pM) until sibling embryos reached st. 20 and were then analyzed by RT-PCR (left panel). Animal caps pre-treated with Noggin mRNA (100 pg) and either control MO or Cdc25B-MO (36 ng) were cultured and analyzed by RT-PCR (right panel). (F) Embryos pre-injected with control MO or FoxM1-MO (36 ng) together with or without Cdc25B mRNA (200 pg) at the one-cell stage were cultured until st. 32 and photographed (left panels). For RT-PCR analysis (right panel), embryos were collected at st. 15.