Npm1^cAand Nras^G12Dcooperate to drive high-penetrance AML. (A) Kaplan- Meier survival curves of wild-type (n = 23), Npm1^cA/+ (n = 34), Nras^G12D/+ (n = 40), Flt3^ITD/+ (n = 39), Npm1^cA/+;Nras^G12D/+ (n = 46), and Npm1^cA/+;Flt3^ITD+/ (n = 40). Double mutant (Npm1^cA/+;Nras^G12D/+ and Npm1^cA/+;Flt3^ITD/+) mice had a significantly shortened survival when compared with single mutants, and Npm1^cA/+;Flt3^ITD had significantly shorter survival than Npm1^cA/+;Nras^G12D/+ mice. (B) Results of independent histopathological analysis of aged moribund mice. Incidence of AML in compound Npm1^cA/+;Nras^G12D/+ and Npm1^cA/+;Flt3^ITD/+ mice is increased in comparison with Npm1^cA/+, Nras^G12D/+, and Flt3^ITD/+ mice. Examples of complete effacement of splenic tissue and infiltration of myeloid blast cells in liver tissue from Npm1^cA/+;Nras^G12D/+ and Npm1^cA/+;Flt3^ITD+/ AMLs are presented. Reduced myeloperoxidase (MPO) staining in diseased tissues is observed in samples categorized as AML without maturation (AML⁻) in comparison with those categorized as AML with maturation (AML⁺). H&E, haematoxylin and eosin.