Transcriptional repressor. Acts on the C-type natriuretic peptide (CNP) promoter. Homodimer or heterodimer. Can form a heterodimer with TSC22D4. Widely expressed in fetal and adult tissues. In aortic endothelial cells, induced by cytokines, including TGFB1. Belongs to the TSC-22/Dip/Bun family.