EPRO-derived neutrophil extracellular traps (NETs) contain histone post translational modification (PTM) marks consistent with transcriptional silencing and hypercitrullination. Murine cell-line derived neutrophils were stimulated and analyzed as in Figure 3 with additional stimulants including ionomycin and PMA. A panel of anti-histone antibody epitopes (top) matching those in Additional file 1: Supplemental Figure 4 is shown, with PTMs according to the PTM key. A strong and saturated band is notable with H3Cit(2,8,17) in EPRO NETs. Film exposure time for all cells were as described in Figure 3 (additional stimulants: 2' for ionomycin and 90' for PMA). PMA, phorbol myristate acetate.