Of importance, a significantly higher level of urine DKK-1 protein was determined in SLE patients relative to healthy individuals (p = 0.0003) (Figure 2(c)), but unlike what is seen in serum, no difference of the abundance of urine DKK-1 was detected between SLE patients with renal involvement and those without LN (p = 0.2633) (Figure 2(c)). This evidence concerns the gene DKK1 and systemic lupus erythematosus.