Transcription factor involved in the control of neuronal differentiation in the brain. Regulates dendrite development and branching, and dendritic spine formation in cortical layers II-III. Also involved in the control of synaptogenesis. In addition, it has probably a broad role in mammalian development as a repressor of developmentally regulated gene expression. May act by preventing binding of positively-activing CCAAT factors to promoters. Component of nf-munr repressor; binds to the matrix attachment regions (MARs) (5' and 3') of the immunoglobulin heavy chain enhancer. Represses T-cell receptor (TCR) beta enhancer function by binding to MARbeta, an ATC-rich DNA sequence located upstream of the TCR beta enhancer. Binds to the TH enhancer; may require the basic helix-loop-helix protein TCF4 as a coactivator. Plays a role in cell cycle progression, in particular at the G1/S transition. As cells progress into S phase, a fraction of CUX1 molecules is proteolytically processed into N-terminally truncated proteins of 110 kDa. While CUX1 only transiently binds to DNA and carries the CCAAT-displacement activity, CDP/Cux p110 makes a stable interaction with DNA and stimulates expression of genes such as POLA1. Interacts with BANP. Interacts with SATB1 (via DNA-binding domains); the interaction inhibits the attachment of both proteins to DNA (By similarity). Phosphorylated by PKA. As cells progress into S phase, a fraction of CUX1 molecules is proteolytically processed into N-terminally truncated proteins of 110 kDa by CTSL. Cell cycle-dependent processing of CUX1 serves to generate a CDP/Cux p110 with distinct DNA binding and transcriptional properties. Belongs to the CUT homeobox family.