Heterogeneity in RAS mutations: One size does not fit all.

Although oncogenic driver mutations in RAS occur in 20% of cancers, heterogeneity in the biologic outputs of different RAS mutants has hampered efforts to develop effective treatments for RAS -mutated cancers. In this issue of Science Signaling , Huynh et al . show that even among KRAS Q61 mutants, the specific amino acid that is substituted substantially affects mutant KRAS biologic activity and oncogenicity.