Furthermore, the importance of understanding the genomic landscape in a given sample was demonstrated by the response of xenograft cells from hypodiploid ALL patients that harboured NRAS and NF1 (VAF >50%) mutations to PI3K/mTOR, but not MEK, inhibitors, despite the detection of pERK and pS6 levels.4 Although further comprehensive genomic and biological investigations are required to fully characterise those patients who may benefit from RAS/RAF/ERK pathway inhibition, here we indicate that there is emerging potential in response to MEK1/2 inhibition in iAMP21-ALL. This evidence concerns the gene MAP2K1 and acute lymphoblastic leukemia.