Transcriptional repressor regulating the expression of a number of genes including SP1 target genes. Probably functions through recruitment of HDAC1 a histone deacetylase involved in chromatin silencing. Interacts with HDAC1. Part of a complex containing at least CDYL, MIER1, MIER2, HDAC1 and HDAC2. Ubiquitously expressed. Isoform 1 is only expressed in testis. Extended N-terminus.