Another conundrum that also remains is whether alterations of the microenvironment observed in cancer are secondary to cancer development, as in the example of the mutation of the JAK2 gene which induces alterations of the bone marrow environment (Arranz et al., 2014), or whether microenvironmental changes occur first (e.g. due to chronic inflammatory conditions) and are sufficient to initiate cancer development. This evidence concerns the gene JAK2 and cancer.