Transcription repressor that binds to the promoter of target genes and prevents their expression. Acts as a negative regulator of epithelial-mesenchymal transition and metastasis in breast cancer. Specifically binds the 5'-CACCC-3' sequence in the promoter of ID1, a key metastasis regulator in breast cancer, and repress its expression. May be a germ cell-specific transcription factor that plays important roles in spermatid differentiation and oocyte development. Exclusively expressed in testis and ovary. Localized to step 3-8 spermatids in testis and growing oocytes in ovary. Belongs to the Sp1 C2H2-type zinc-finger protein family.