MAPK1 and neoplasm: For instance, the in vitro models A375, 293T, SKMEL-19, and WM266.4 cell lines showed that the mutants ERK1 Tyr53His/ERK2 Tyr36His/Asn, ERK1 Gly54Ala/ERK2 Gly37Ser, ERK1 Pro75Lys/ERK2 Pro58Lys, ERK1 Tyr81Cys/ ERK2 Tyr64Asn, and ERK1 Cys82Tyr/ERK2 Cys65Tyr had resistance to ERK inhibitors, favoring tumor progression [158].