BMI1 and neoplasm: We show that BMI1 binds MAPK-regulated genes specifically when CHD7 is expressed and that the CHD7-BMI1-MAPK regulatory axis underpins the anti-tumor activity of BMI1 and MAPK/ERK inhibitors in vitro and in an in vivo preclinical model of BMI1High;CHD7Low MB where it significantly extends survival of xenografted mice.