Histone modifications form a cell-type-specific chromosomal bar code that persists through the cell cycle

Post-translational modifications (PTM) of core histones seem to be involved in chromatin structural transitions as cells transit the cell cycle, but how remains unclear. Here, we use ChIP-seq in cell-cycle sorted cultured cells to define histone modification patterns through the cell cycle. We used cell-cycle sorting methods (fluorescence-activated cell sorting (FACS), centrifugal elutriation and mitotic shakeoff) in two cultured cell lines, HeLa and lymphoblastoid cells. We carried out ChIP-seq for histone modifications on chromatin from cells sorted into G1 phase, G2M phase or mitosis (HeLa only).