Of note, epithelial cell-specific Fli1 knockout mice (Fli1Pflox/floxP; K14-CreP+/−P mice), which possess epithelial cells with SSc-like phenotypical features, spontaneously develop dermal and esophageal fibrosis due to the activation of epithelial cells in the skin and esophagus. This evidence concerns the gene PPP1R15B and systemic sclerosis.