MAP2K1 and neoplasm: Consistent with the aforementioned changes in key SOS2-RAS associated pathway mediators, IHC staining of tumor node sections revealed that the levels of SOS2, Ki67 and SOS2-RAS associated downstream mediators (p-MEK1/2, p-ERK1/2 and p-AKT) were remarkably inhibited by sulfarotene in the high SOS2 expressors (Fig. 8 g, h).