This gene encodes a member of the Ste20 family of serine/threonine protein kinases, and is similar to several known polo-like kinase kinases. Mice deficient for this gene product are viable, but exhibit altered integrin-mediated lymphocyte adhesion characteristics. The orthologous gene product in humans can associate with and phosphorylate polo-like kinase 1, and overexpression of a kinase-dead version of the protein interferes with normal cell cycle progression. [provided by RefSeq, Jul 2008]