PTEN loss characterizes a murine model of T-ALL where leukemogenesis was induced by overexpression of constitutively-active tropomyosin-related kinase A (ΔTRKA) or of TRKB/brain-derived neurotrophic factor (BDNF, the TRKB ligand) in Lin−/Sca1+/c-Kit+ HSCs [52]. The gene discussed is PTEN; the disease is acute lymphoblastic leukemia.