Based on studies in mice, RUNX2 forms a complex with ZNF521 (ZNP521) and a histone deacetylase HDAC3. Binding to ZNF521 does not inhibit RUNX2 binding to target genes, such as the BGLAP (Osteocalcin) gene promoter, but inhibits RUNX2-mediated activation of these genes. HDAC3 is needed for ZNF521 to inhibit RUNX2-mediated transcription from the BGLAP promoter. Action of ZNF521 antagonizes RUNX2 during mesenchymal commitment to the osteoblast lineage and during osteoblast maturation (Hesse et al. 2010).