NEGotiating Cell Identity through Regulated Cytoplasmic Polyadenylation.

In this issue of Developmental Cell, Elewa et al. (2015) show that combinatorial action of RNA binding proteins modulates poly(A) tail length of maternal mRNAs, leading to asymmetric expression of a cell fate determinant in early C. elegans embryos. Genome-wide profiling suggests this mechanism may be widely used to establish cell identities.