SOS1 and neoplasm: The above observations showing the remarkable impact caused by SOS1 ablation on tumor initiation, progression and stromal microenvironment (Figs. 1–3) were generated in an experimental system involving wide-body elimination of SOS1 or SOS2 in our KRASG12D mouse model and, therefore, we could not discern whether those clinically beneficial effects are cell-autonomous or not.