LSCs of CP CML are thought to lie within the haematopoietic stem cell (HSC) population immunophenotypically defined as positive for CD34 and negative for CD38 surface markers (CD34+CD38−) [11] that stands atop the haematopoietic hierarchy (Figure 1). The gene discussed is CD38; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.