Assay #1: Fully biologically active when compared to standard. The ED50 as determined by a cell proliferation assay using IL-6-dependent murine 7TD1 cells is less than 0.1 ng/ml, corresponding to a specific activity of > 1.0 × 107 IU/mg.Assay #2: Fully biologically active when compared to standard. The ED50 as determined by a cell proliferation assay using IL-6-dependent murine T1165 cells is less than 0.8 ng/ml, corresponding to a specific activity of > 1.25 × 106 IU/mg.