Fig 1C indicates a rationale for why p-rpS6, with a much stronger signal than p-mTOR, is a useful surrogate for mTORC1 activity. AML samples were selected to provide a wide range of cytogenetic and molecular abnormalities (Table 1). The gating strategy for comparing Ki-67 positive and negative blasts is indicated (Fig 1D). The use of CD45/side scatter (SSC) gating to distinguish blasts from lymphocytes and from leukaemia cells with cytoplasmic maturation and monocytoid differentiation (SSChigh/CD45high) is well described in the literature [34–37]. Here, RPS6 is linked to leukemia.