HDAC9 and medulloblastoma: Both ZNF521 and ZNF423 have N-terminal motifs that interact with the HDAC-containing NuRD complex [5, 6, 61], and the integrity of this motif has been shown to be essential for the promotion of growth and tumorigenicity of medulloblastoma cells [10]; in addition, Zfp521 is also known to interact with HDAC3 and HDAC4 that are instrumental in the regulatory functions of Zfp521 in growth plate chondrocytes and osteoblasts [14, 15].