Treatments with Ro5-3335 phenocopy cbfb^−/− hematopoietic defects. Bar graphs showing the effect of Ro5-3335 treatment on c-myb expression in WT embryos from 24 hpf to 36 hpf (A) and from 24 hpf to 3 dpf (B). Percentages of embryos with unaffected (white bars), reduced (gray bars), and absence of (black bars) c-myb expression are depicted on the y-axis. Right panels show representative images of different categories of c-myb expression (1, unaffected; 2, reduced; 3, absent). (C-F) Confocal time-lapse imaging of the AGM region of tg(flk1:moesin1-eGFP) embryos between 48 and 58 hpf (5-minute intervals for 10 hours), which were treated with DMSO (0.1%) or Ro5-3335 (5 μM) from 24 hpf. Panel C shows bar graphs representing average numbers of eGFP⁺ HSCs leaving the AGM in DMSO-treated (n = 3) and Ro5-3335–treated (n = 5) embryos. ***P < .001 vs DMSO. Panel D shows a lateral view of a 2-dpf embryo, and the box indicates the region that was imaged by time lapse. Panels E and F show 2 representative video frames of fluorescence images (Z = 6-8) of the same AGM region of a DMSO-treated tg(flk1:moesin1-eGFP) embryo at 2 time points (45 minutes apart). The red and the white dots in panel E mark 2 eGFP⁺ cells within the AGM. The eGFP⁺ cell marked in red in panel E is no longer present in panel F, indicating that it had been released into the axial vein. AV, axial vein.