MAPK1 and neoplasm: Furthermore, the effects of SIAIS562055 on SOS1 degradation and pERK inhibition in MIA PaCa-2 tumor tissues correlated with the in vitro results, as confirmed by the significant suppression of SOS1/KRAS/ERK signaling and induction of caspase-3 cleavage upon treatment with SIAIS562055 (Fig. 3D; Supplementary Fig. S5).