In direct ELISAs, approximately 15% cross-reactivity with recombinant human (rh) IGFBP-6 is observed and less than 1% cross-reactivity with rhIGFBP-1, rhIGFBP-2, rhIGFBP-3, rhIGFBP-4, and rhIGFBP-5 is observed. Reconstitute at 0.2 mg/mL in sterile PBS. E