Salt-inducible kinase family (SIKs) proteins are thought to have a role in steroidogenesis, adipogenesis or regulation of tumor malignancy. Three members (SIK1, SIK2 and SIK3) in the SIK family have been identified thus far. Their kinase domain sequences are closely homologous to those of AMP-activated protein kinase (AMPK). SIK3 can be phosphorylated by a tumor-suppressor kinase LKB1. It is highly and preferentially expressed in ovarian tumors but not in adenomyosis and leiomyoma and may be a potential diagnostic marker for ovarian cancers.Synonyms: EC=2.7.11.1, KIAA0999, QSK, SIK-3, SIK3, Salt-inducible kinase 3, Serine/threonine-protein kinase QSK