OLIG1 and neoplasm: Given the significant reduction in GFP+ tumor cells in Olig1/2F/+; H2bF/+ mice at P20, we further investigated whether Olig1/2 knockout suppresses tumor initiation by systematically analyzing Olig1/2F/+; H2bF/+ and Olig1/2F/+; ISF/+ mice at a later stage (P40).