KiSS-1 has been reported to suppress metastases of melanomas and breast carcinomas without affecting tumorigenicity. Human KiSS-1 transcripts are predominately expressed in the brain and placenta. Expression of KiSS-1 reduces the level of NFkB p50/p65 binding to the MMP9 promoter and correlates with diminished expression of the 92 kDa type IV collagenase (MMP-9). KiSS-1 may regulate events downstream of cell-matrix adhesion in mechanisms involving cytoskeletal reorganization.