酵素活性:Assay #1: Fully biologically active when compared to standard. The ED50 as determined by the dose- dependent stimulation of the proliferation of murine NFS-60 cells is less than 5.0 ng/ml, corresponding to a specific activity of > 2 × 105 IU/mg. Assay #2: The ED50 as determined by a cell proliferation assay using human TF-1 cells is less than 0.05 ng/ml, corresponding to a specific activity of > 2.0 × 107 IU/mg.