STAT1 and melanoma: Activation of JAK/STAT signaling promotes tumor growth and invasion as well as immunosuppression.11 Moreover, PD-L1, one of the hot spots in current immunotherapy, was reported to be regulated by JAK/STAT signaling in many cell types, especially JAK2/STAT1 and JAK2/STAT3.12 However, one group reported that PD-L1 was also regulated by interferon-gamma–JAK1/JAK2–STAT1/STAT2/STAT3–IRF1 axis in melanoma cells.13