WFDC12 is a member of the WAP-type four-disulfide core (WFDC) domain family. The WFDC domain, or WAP signature motif, contains eight cysteines forming four disulfide bonds at the core of the protein, and functions as a protease inhibitor. Recombinant human WFDC12 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.