HLA-G and uremia: We collected the US with the same phosphate levels from three patients; surprisingly, the US induced Runx2 expression and ALP activity was not consistent, while the same concentration of inorganic phosphorus has better repeatability (Supplemental Fig. 2), since other uremia toxins, such as β2-microglobulin, indoxyl sulfate, homocysteine, uric acid, and parathyroid hormone may frustrate the pro-calcification effect of US [24].