JAK3 and severe combined immunodeficiency: The loss of expression of the IL-2Rγ/JAK3 couple in RCC is not induced by mutations [55], as observed in syndromes of severe combined immunodeficiency (SCID) [9] but probably related to different mechanisms of post transcriptional control targeting IL-2Rγ could involve its mRNA stability [56], while the loss of JAK3 expression in vitro and its weak expression in vivo may depend on the level of expression and activation of the tyrosine phosphatase SHP1, which negatively regulates JAK3 [57].