biological activity
fully biologically active when compared to standard. the ed50 as determined by a cell proliferation assay using serum free human mcf-7 cells is less than 2 ng/ml, corresponding to a specific activity of > 5.0 × 105 iu/mg.

physical appearance
sterile filtered white lyophilized (freeze-dried) powder.

formulation
lyophilized from a 0.2 μm filtered concentrated solution in pbs, ph 7.0.