FSTL1 and esophageal squamous cell carcinoma: In cancer, FSTL1 plays a critical role in tumor malignancy, including tumor proliferation, clonogenicity, invasion, metastasis, self-renewal, and chemoresistance, in various types of cancer, such as breast cancer [31], lung cancer [35], colorectal cancer [34], head and neck cancer [33], and esophageal squamous cell carcinoma [32].