The molecular mechanisms underlying the correlation of MCL1- and MEK1-protein levels and response to S63845 and trametinib may be related to the phenomenon of oncogene addiction, where the tumor relies on a dominant oncogene or mechanism for growth and survival, so that inhibition of this specific oncogene/pathway is sufficient to halt the neoplastic phenotype [22,23]. Here, MCL1 is linked to neoplasm.