FSTL1 and esophageal squamous cell carcinoma: Studies have showed that FSTL1 was involved in tumor development and tumor immunity by a variety of mechanisms, such as promoting metastasis and chemoresistance through NFκB-BMP signaling pathway in esophageal squamous cell carcinoma [15], activating the focal adhesion signaling pathway to promotes colorectal cancer [14], and causing immune dysfunction in lung cancer [18] and tumor with bone metastasis [37].