Primary mouse embryonic fibroblasts (PMEF) derived from Suvar39h double knockout (dn) mice and B-cell lymphomas formed in Suvar39h dn mice show a polyploid DNA content (Peters et al, 2001), and mouse oocytes devoid of SETDB1 show misaligned chromosomes and multiple spindles (Eymery et al, 2016; Kim et al, 2016). This evidence concerns the gene SETDB1 and B-cell non-Hodgkin lymphoma.