JAK2 and neoplasm: The release of adenosine or indoleamine 2,3-dioxygenase in the microenvironment or mutations of the genes encoding JAK1 or JAK2 (key intracellular signalling mediating tumour sensitivity to interferon) or the gene encoding β-2-microglobulin (involved in folding and transport of MHC class I molecules) are recognized causes of acquired resistance [42].