BCL6B and neoplasm: As indicated by morphologic images (Fig. 5a), H&E staining (Fig. 5b) and Pan-Cytokeratin immunostaining (Additional file 2: Figure S2), the demethylation drug 5-Aza obviously decreased tumour number (Fig. 5c) and maximum tumour size (Fig. 5d) by greater than 70% in BaP-treated wildtype mice compared to saline controls, but only had a minor role in BaP-treated Bcl6b−/− mice.