In addition, induced cells upregulate multiple genes encoding signal transduction molecules, including multiple MAPK genes and show signs of chronic signalling by displaying an increase in expression of the MAPK inducible TF genes Fos, Fosb and JunD. RUNX1-ETO cannot cause leukaemia on its own but requires secondary mutations, mostly in growth factor receptor genes13, 36, 37. Here, FOSB is linked to leukemia.