Comparison of the effectiveness of FBS, rabbit sera, BSA, and serum proteins in the prevention of calcification in cell culture. The efficacy of proteins and sera to inhibit calcification is expressed as C1/2 (Y-axis), representing a parameter for the concentration of serum needed to inhibit one half of serum depletion-induced calcification. For the serum protein assessment, the C1/2 values were normalized to the percentage of the serum on the basis of their concentrations in the serum. The C1/2 values were obtained from 3 independent experiments with sera or proteins precipitated by 60% ethanol. One-Way ANOVA analysis was used to determine statistical significance among these parameters. No significance was noted except that the C1/2 from BSA was markedly higher than those from sera or total serum proteins, meaning that BSA was much less effective than others (p < 0.05). The initial Ca × P ion product in culture media was 9.37 mM2.