Fig. 7. Summary of HOW functions in early mesoderm development. Following mesoderm specification, levels of HOW(L) are increased in the presumptive mesoderm in order to inhibit the levels of string (cdc25) mRNA and to therefore arrest cell divisions during mesoderm invagination. During mesoderm spreading, HOW is essential to repress the levels of a set of maternal mRNAs (falten, CG31638 and lap), as well as miple, the high levels of which might induce ectopic MAPK activation in the mesoderm during spreading.