To assess this, we used HAP1 cells, a near-haploid cell line derived from KBM-7 chronic myeloid leukaemia cells, where either SIRT1, 3 or 6 had been deleted by CRISPR-Cas9 mutagenesis. The gene discussed is SIRT1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.