A mineralized connective tissue known as cementum covers the root surfaces of teeth and is required for maturation of periodontal tissue. CEMP1 (cementum protein 1), also designated CP23 or cementoblastoma-derived protein 1, is a 247 amino acid nuclear and cytoplasmic protein that is thought to regulate cementoblast behavior. Expressed specifically in periodontal ligament and cementum, CEMP1 may play a role in differentiation and mineralization of non-osteogenic cells. The gene encoding CEMP1 maps to human chromosome 6, which contains 170 million base pairs and comprises nearly 6% of the human genome. Deletion of a portion of the q arm of chromosome 6 is associated with early onset intestinal cancer, suggesting the presence of a cancer susceptibility locus. Additionally, Porphyria cutanea tarda, Parkinson's disease, Stickler syndrome and a susceptibility to bipolar disorder are all associated with genes that map to chromosome 6.