All the embryo's a stage, and Olig2 in its time plays many parts.

Olig2 is essential for the selection of motor neuron and oligodendrocyte fates and the choice of neural progenitors to either proliferate or differentiate. Three new studies demonstrate that these diverse actions of Olig2 are gated by phosphorylation at two distinct motifs and that Olig2's proliferative function acts in opposition to the p53 tumor suppressor pathway.