JAK1 and primary cutaneous T-cell non-Hodgkin lymphoma: Aberrant IL-7 singling is believed to a play role in the early stages of CTCL, as activation of STAT3 and STAT5 provides a survival signal to malignant T-cells until the later stages, in which there is often cytokine-independent JAK1 and JAK3 signaling [46,47,48].