The WFIKKN1 protein contains a WAP domain, follistatin domain, immunoglobulin domain, two tandem Kunitz domains, and an NTR domain. This gene encodes a WFIKKN1-related protein which has the same domain organization as the WFIKKN1 protein. The WAP-type, follistatin type, Kunitz-type, and NTR-type protease inhibitory domains may control the action of multiple types of proteases.