Hmg20b is the component of a BHC histone deacetylase complex that contains HDAC1, HDAC2, HMG20B/BRAF35, AOF2/LSD1, RCOR1/CoREST and PHF21A/BHC80. Hmg20b is required for correct progression through G2 phase of the cell cycle and entry into mitosis Hmg20b is also required for RCOR1/CoREST mediated repression of neuronal specific gene promoters.