SOS1 and cancer: Intriguingly, although neither SHP2 nor SOS1 inhibitors were able to inhibit cancer cells with KRAS Q61 mutations as single agents [133,135], both were able to enhance the efficacy of the MEK inhibitor trametinib in xenograft models harboring KRAS Q61 mutations [113,135], suggesting that inhibiting proximal RTK signaling might be broadly effective in combination therapies for RAS-mutated tumors harboring G12, G13, or Q61 mutations.