MARK2 and acute lymphoblastic leukemia: In many cells, signaling pathways mediated by PtdIns(3,4,5)P3 and the serine/threonine kinase AKT control nutrient transport.33 However, in normal effector T cells the regulation of nutrient uptake is phosphatidylinositol-3 kinase (PI3K)/AKT independent.3, 4 The Ptenfl/flLck-Cre+ mouse model allows the isolation of PTEN−/− non-transformed thymocytes from young (4–6 week old) mice.34 These PTEN−/− non-transformed thymocytes have been well characterized25, 34 and are known to be polyclonal and lack the secondary mutations associated with T-ALL.