Fig. 6. The initial termination of E2f1-target gene expression does not require Rbf1. Rbf1¹⁴ maternal and zygotic null embryos were pulse-labeled with BrdU for 15 minutes and stained for E2f1 (green) and BrdU incorporation (cyan). RnrS expression was detected by FISH (red). (A) Stage 10 embryo; bracket marks the dorsal epidermis in S₁₆ and the bar indicates cycle 15. (B) Stage 11 embryo; the epidermal cells are in G2₁₆. (C) Stage 13 embryo; arrow indicates epidermal cells arrested in G1₁₇ and the bracket denotes epidermal cells inappropriately incorporating BrdU. Scale bar: 50 µm.