secreted phosphoprotein 1(SPP1) Homo sapiens The protein encoded by this gene is involved inThe attachment of osteoclasts toThe mineralized bone matrix.The encoded protein is secreted and binds hydroxyapatite with high affinity.The osteoclast vitronectin receptor is found inThe cell membrane and may be involved inThe binding to this protein. This protein is also a cytokine that upregulates expression of interferon-gamma and interleukin-12. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2011],