Increasing evidence demonstrates JAKs as a prognostic biomarker and therapeutic target for many cancers or other diseases, such as JAK3 for renal cell carcinoma, JAK2 for acute lymphoblastic leukemia [9], JAK2 for skin cutaneous melanoma [10], and TYK2 for hepatocellular carcinoma [11]. The gene discussed is JAK2; the disease is cutaneous melanoma.