The role of A3B in tumor initiation was first investigated in a mouse strain combining a new loxP-STOP-loxP (LSL) inducible human A3B transgenic model (Rosa26LSL-A3Bi)20 with a Cre-inducible EGFRL858R-driven lung cancer mouse model (TetO-EGFRL858R; Rosa26LNL-tTA) to generate EA3B (TetO-EGFRL858R; Rosa26LNL-tTA/LSL-A3Bi)11,12,21 mice (Fig. 1a). Here, APOBEC3B is linked to lung cancer.