KRAS and neoplasm: Importantly, the inability of Flag-KRASC118S to restore the reduced tumor growth upon knocking down endogenous wild-type KRAS was rescued if Flag-KRASC118S was engineered to contain an activating (G12V) mutation, as evident from the similar growth kinetics (Fig 3B) and tumor size and weight at endpoint between the KRAS-knockdown cells expressing wild-type Flag-KRAS and those expressing Flag-KRASC118S,G12V (Fig 3B–3D).