For example GGTCAATCT or GGCCAATCT are CAAT box sequences.
This is a sequence of nucleotides found in a conserved region of 5' DNA end located "upstream" (direction) of the start points of eukaryotic transcription units. Transcription factors binds to it and it is believed to determine the efficiency of transcription. These boxes are found in many promoters at -75 bp.