Fig. 8. Posterior Hox proteins function as transcriptional activators leading to
the Cdx-mediated inhibition of hindbrain formation. Expression of
krox20 in wild-type control embryos (A) and embryos that
received an injection of 25 pg of hoxa9a RNA (B), 25 pg of
hoxb9a RNA (C), cdx1a/4MOs and hoxa9a RNA
(D), cdx1a/4MOs and hoxb9a RNA (E),
cdx1a/4MOs and 25 pg of En-hoxa9a RNA (F),
cdx1a/4MOs and 25 pg of En-hoxb9a RNA (G),
cdx1a/4MOs and 25 pg of VP-hoxa9a RNA (H) or
cdx1a/4MOs and 25 pg of VP-hoxb9a RNA (I).
Overexpression of hoxa9a, hoxb9a, VP-hoxa9a or VP-hoxb9a
suppresses the expression of krox20 in its normal and ectopic
positions. Overexpression of En-hoxa9a or En-hoxb9a did not
suppress the ectopic krox20 expression (marked by arrowheads). Scale
bar: 100 µm.