The Polo-like protein kinases (Plks) are a conserved family of enzymes that play a variety of roles in the passage of cells through M phase (for reviews see Glover et al., 1998; Nigg, 1998). Named after the Drosophila polo gene originally identified through a recessive maternal effect lethal mutation, conserved Plk homologues have been identified in yeast, Xenopus, C. elegans and mammals. The i...
