In direct ELISAs, approximately 5% cross-reactivity with recombinant human (rh) SULT1A1 and rhSULT1A3 is observed and less than 2% cross-reactivity with rhSULT2A1, rhSULT4A1, rhSULT2B1, and rhSULT1E1 is observed. Reconstitute at 0.2 mg/mL in sterile PBS.