JAK3 and scleroderma: JAK1 and JAK2 but not JAK3 inhibitors alleviated skin fibrosis in different aspects, such as morphology and dermal thickness, and the JAK2 inhibitor alleviated skin fibrosis the most (Figures 1A–E), demonstrating that JAK inhibition prevented fibrosis in a BLM-induced mouse model of scleroderma.