STAT3 and esophageal squamous cell carcinoma: For example, esophageal squamous cell carcinoma (ESCC)‐associated fibroblasts activate signal transducing activator of transcription 3 (STAT3) signaling by paracrine exosomal miR‐21 to induce monocytes to transform into M‐MDSCs, thereby promoting cisplatin resistance.107