MAPK1 and neoplasm: To explore this mechanistically, we profiled paradoxical ERK activation by vemurafenib, dabrafenib, encorafenib (LGX818), and PLX8394, demonstrating that vemurafenib induces ERK activation the greatest, while dabrafenib and encorafenib have higher “paradox indices”, defined as the pERK activation EC80 divided by the IC80 against A375, corresponding to wider therapeutic windows for achieving tumor inhibition without paradoxical ERK activation.