SMN1 and esophageal squamous cell carcinoma: For example, PDGFRα expression in CAF was an essential factor in the prognosis of ESCC; PDGFRβ expression was associated with poorly differentiated tumors; SMA expression in ESCC stromal fibroblasts was associated with a large size of the tumor, advanced pT stage, lymph node metastasis, and poor prognosis.