SP1 and glioma: To investigate the impact of the disruption of these interactions on tumorigenesis, we transfected an astrocyte cell line (Astro#40) and a glioma cell line (U87) with plasmid constructions encoding for peptides mimicking certain amino-acid regions implicated in the interactions existing between DNMT1 and DMAP1, DNMT3b, PCNA, EZH2, HDAC1, Sp1 and HP1β (Figure 1A and Additional file 1: Figure S1).