| Overexpression of cyclin D 1 and HDAC 3 significantly enhanced the transcriptional repression activity of INSM 1 on the neuroD / beta2 promoter . ^^^ A further chromatin immunoprecipitation assay confirmed that HDAC 3 occupies this same region of the neuroD / beta2 promoter , by forming a transcription complex with INSM 1 . ^^^ |