DKK1 and plasma cell myeloma: Although the control group (n=12) was smaller than the OS group (n=37), and the median age of the unaffected individuals was slightly higher (by approximately 7 years), the control Dkk-1 values were similar to the normal levels reported by Tian et al (2003), who demonstrated that elevated levels of serum Dkk-1 were coincident with the osteolytic lesions seen in most cases of multiple myeloma (Figure 1A).