ABCB4 and neoplasm: We observed up-regulated gene expression of tumour markers including tumour necrosis factor α induced protein (Tnfaip; A20), secreted phospho protein 1 (Ssp1, OPN) and α-feto protein (Afp) (Supplementary Fig. 3C) in 12-week-old Tnfr1−/−/Mdr2−/− mice27,28.