Our data using cell lines and primary patient samples support the correlation between Erk2 activation and Bcr/Abl levels in the generation of an IM resistant phenotype, suggesting that the use of Erk2 signaling pathway inhibitors -that target the Ras/Raf/ERK route- could represent a complementary therapy in those patients with advanced stages of CML, especially in those who are refractory to IM based therapy [45]. This evidence concerns the gene MAPK1 and chronic myelogenous leukemia, BCR-ABL1 positive.