SOS1 and neoplasm: Of note, our observation of significant CAFs impairment in the TME when SOS1KO mice were injected with KPB6 cells, but not when WT mice were injected with SOS1/2WT, SOS1KO, or SOS2KO KPB6 cells, strongly suggests that the role of SOS1 in altering the TME in the recipient mice is separate from its impact on the growth of tumor initiating cells.