When expression was restricted to the BM compartment, upon BM transplantation in recipient mice, Nras G12D/+ lead to CMML in 95% of mice, in some of which the up-regulation of oncogenic Nras allele through uniparental disomy (UPD) was observed, and to acute T ALL in 8% of mice, in some of which up-regulation of Nras wild type allele was observed. Here, NRAS is linked to acute lymphoblastic leukemia.