CD34 and leukemia: In the first cluster that we chose to highlight, imatinib, a small molecule that is known to be a tyrosine kinase inhibitor36, has signatures that were generated from multiple cell lines, including K562 leukaemia cell line (GSE1922), chronic myelogenous leukaemia (CML) CD34+ cells (GSE12211) and three other CML cell lines (KU-812, KCL-22, JURL-MK1) (GSE24493), which cluster together with knockdown signatures of NRAS in melanoma cell lines (GSE12445) (Fig. 4b).