In the April 21st edition of Developmental Cell, A. Rossa et al. from the Rockefeller University reported their comparative study on the family of miR-430/427/302 and their function during embryogenesis. The investigators found that miR-302 in human embryonic stem cells (hESCs) and its ortholog miR-427 in Xenopus laevis targets specific ligands of the Nodal pathway. The experimental data revealed that miR-302 promotes the mesodermal lineage at the expense of neuroectoderm formation in hESCs. In Xenopus embryos, depletion of miR-427 results in severe dorsal mesodermal patterning defects. The authors concluded that their findings "suggest a crucial role for the miR-430/427/302 family in vertebrated embryogenesis by controlling germ layer specification."