 The t(9;22)(q34;q11) or Philadelphia chromosome creates a BCR-ABL1 fusion gene encoding for a chimeric BCR-ABL1 protein.     ///    "In parallel, the mechanistic understanding of Ph(+) ALL expanded exponentially through careful mapping of pathways downstream of BCR-ABL1, the discovery of mutations in master regulators of B-cell development such as IKZF1 (Ikaros), PAX5, and early B-cell factor (EBF), the recognition of the complex clonal architecture of Ph(+) ALL, and the delineation of genomic, epigenetic, and signaling abnormalities contributing to relapse and resistance. "