This gene encodes a member of the serine/threonine kinase family. The encoded protein, a known tumor suppressor, activates (via phosphorylation) adenine monophosphate-activated protein kinase (AMPK) and AMPK-related kinase proteins. This upstream regulation of the AMPK pathway is thought to regulate a number of different processes, including cell metabolism, cell polarity, apoptosis and DNA damage response. Mutations in a similar gene in human have been associated with Peutz-Jeghers syndrome. Alternative splicing results in multiple transcript variants, including the S isoform which plays a potential role in spermiogenesis. [provided by RefSeq, Sep 2014]