A ubiquitous protein-serine kinase, initially implicated in glycogen regulation, has surfaced unexpectedly in the fields of nuclear oncogenes and fruitfly development. This unusual linkage may reflect the role of this kinase in phosphorylating proteins normally activated by dephosphorylation, thus providing a priming function. Loss of such a primer would result in constitutive activation of substrates, a scenario concordant with the dramatic and pleiotropic phenotype observed in Drosophila null mutants.