After the discovery of pluripotency factors capable of reprogramming blood cells, iPSC lines have been generated from a patient with a myeloproliferative disorder bearing the JAK2-V617F mutation (Ye et al., 2009), CML cell lines (Carette et al., 2010), primary bone marrow cells of chronic phase CML patients (Bedel et al., 2013; Hu et al., 2011; Kumano et al., 2012), juvenile myelomonocytic leukemia (Gandre-Babbe et al., 2013), and mouse MLL-AF9 leukemia cells (Liu et al., 2013). Here, JAK2 is linked to juvenile myelomonocytic leukemia.