SPI1 and acute myeloid leukemia: The PU.1-14kb plays a key role in PU.1 expression in haematopoietic stem/progenitor cells (HSPCs) and mature haematopoietic cell types; its deletion results in an 80% loss of PU.1 gene expression and acute myeloid leukaemia (AML) in mice (Rosenbauer et al., 2004), while mutation of an (autoregulatory) Ets site within the PU.1-14kb causes a 66% reduction in PU.1 gene expression, which leads to haematopoietic stem cell exhaustion (Staber et al., 2013).