Casein kinase I isoform gamma-2 (CK1g) ecoded by the CSNK1G2 gene is a member of the large casein kinase I (CKI) family, which belongs to the intracellular serine/threonine kinases. The CKI family includes several other isoforms (alpha, beta, gamma, and delta). Casein kinase 1 gamma (CK1gamma) is associated with the cell membrane and binds to LRP. CK1gamma was found to be needed for Wnt signaling through LRP. CSNK1G2 inhibits Smad3-mediated TGF-beta responses including induction of target genes and cell growth arrest, and this inhibition is dependent on CSNK1G2 kinase activity. The overexpression of CSNK1G2 in human cancers, may act as an oncoprotein during tumorigenesis.