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Fig. 2. Dll1 is required for normal expression of both rostral and caudal genes,
and Mesp2 suppresses the caudal half property in both Dll1-dependent and
Dll1-independent manners. Expression of Cer1 is usually observed as
two or three stripes, finally localizing to the rostral half of nascent somite
in the wild-type embryo (A). Cer1 expression is almost lost in both
Dll1-null and Mesp2-null embryos (B,C), as well as the Dll1/Mesp2 double-null
embryo (D). Normal stripes of Uncx4.1 expression, localizing to the
caudal half of each somite (E), are completely lost in the Dll1-null embryo
(F). In Mesp2-null embryos, expression of both Dll1
(Fig. 1) and Uncx4.1
is strongly expanded (G). However, the additional loss of Mesp2 in
the Dll1-null embryo results in an expanded pattern of Uncx4.1
expression (H). Genetic cascades are also shown.