a, Strategy for the generation of resistant clones. HSPC, haematopoietic stem and progenitor cells. b, Resistance to I-BET demonstrated in cell proliferation assays performed in biological triplicate (mean ± s.d.). c, Resistance to JQ1 demonstrated in cell proliferation assays performed in biological triplicate (mean ± s.d.). d, Resistance to I-BET in clonogenic assays performed in biological duplicate (mean ± s.e.m.). e, Resistance to I-BET-mediated induction of apoptosis in biological triplicate experiments (mean ± s.e.m.). f, Resistant clones do not demonstrate cell cycle arrest in biological triplicate experiments (mean ± s.e.m.). g, Resistance to shRNA-mediated knockdown of Brd4 in biological duplicate experiments (mean ± s.e.m.). h, i, Kaplan-Meier curve of secondary syngeneic transplant of sensitive (h) and resistant (i) clones (n = 6 per group, statistical significance calculated using a log-rank test). Dotted line denotes treatment starting on day 9.